Unified Standard Class 3B Plug Gauges

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Thread Size

Thread Fit

Unified Standard Class 2B

Unified Standard Class 3B

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Certificate Type

Accuracy Certificate Traceable to NIST

Calibration Certificate Traceable to NIST

Thread Direction

Left Hand

Right Hand

Gauge Measurement Type

No-Go

Material

Tool Steel

Finish

Chrome Plated

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

REACH

Compliant

RoHS

Compliant

Size-Checking Gauge Class

DFARS Specialty Metals

Exempt

Hardness

Rockwell C70

Export Control Classification Number (ECCN)

EAR99

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192 Products

Go/No-Go Threaded Plug Gauges with Handle

Speed up thread tolerance checks—the handle on these gauges gives you a good grip to quickly thread and unthread go or no-go gauges. Use these gauges to make sure nuts, tapped holes, and other parts fall within tolerance. All are precisely manufactured to confirm thread fit. If the plug gauges wear down, you can insert new ones (not included) onto the taperlock handle.

A part is within tolerance if it’s easy to thread the go gauge into the part but difficult to thread the no-go gauge more than two turns.

Go/no-go gauges have both a go gauge on one end of the handle and a no-go gauge on the other to speed up tests. Go gauges check the minimum internal thread size. No-go gauges check the maximum internal thread size.

Class X Gauge

Double-Ended Taperlock

Handle

Accuracy Certificate Traceable to NIST—Gauges with an accuracy certificate traceable to NIST include verification from the manufacturer that their thread sizes are within tolerance. The certificate is also known as a certificate of compliance or a short-form certification.

Calibration Certificate Traceable to NIST—Gauges with a calibration certificate traceable to NIST were calibrated in a lab. The certificate, sometimes called a test report or long-form certificate, details the tested measurements.

For Thread Fit—Thread fit designates the tightness or looseness of mating threads.

	Thread Size	Thread Type	Pitch Dia. Tolerance	Hardness	Material	Features	For Thread Fit		Each
Go/No-Go Gauges



		0-80	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A501	0000000


		1-72	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A503	000000
		2-56	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A504	000000
		3-48	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A506	000000
		4-40	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A508	000000
		4-48	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A509	000000
		5-40	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A511	000000
		6-32	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A513	000000
		6-40	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A514	000000
		8-32	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A515	000000
		8-36	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A516	000000


		10-24	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A517	000000
		10-32	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A518	000000
		12-24	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A519	000000
		1/4"-20	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A522	00000
		1/4"-28	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A523	00000
		5/16"-18	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A524	00000
		5/16"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A525	00000
		3/8"-16	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A526	00000
		3/8"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A527	00000
		7/16"-14	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A528	00000


		7/16"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A529	00000
		1/2"-13	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A531	000000
		1/2"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A532	000000
		9/16"-18	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A153	000000
		5/8"-11	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A533	000000
		5/8"-18	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A534	000000
		3/4"-10	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A535	000000
		3/4"-16	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A536	000000
		7/8"-9	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A537	000000
		7/8"-14	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A538	000000


		1"-8	UNC	-0.0004" to 0.0004"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A539	000000
		1"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A541	000000
		1 1/8"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A544	000000
		1 1/4"-7	UNC	-0.0004" to 0.0004"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A545	000000
		1 1/4"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A546	000000


		Go/No-Go Gauges with Accuracy Certificate Traceable to NIST



				2-64	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A301	000000


				3-56	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A304	000000
				5-44	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A305	000000
				12-28	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A302	000000
				12-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A306	000000
				1/4"-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A307	000000
				5/16"-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A308	000000
				3/8"-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A309	000000
				7/16"-28	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A311	000000
1/2"-28				UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A312	000000
9/16"-24	UNEF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A313	000000


5/8"-24	UNEF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A314	000000
11/16"-24	UNEF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A315	000000
3/4"-20	UNEF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A316	000000
7/8"-20	UNEF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A317	000000
1"-14	UNS			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A318	000000
1"-20	UNEF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A319	000000
1 3/8"-12	UNF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A321	000000
1 1/2"-12	UNF			-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	2366A303	000000


Go/No-Go Gauges with Calibration Certificate Traceable to NIST



				0-80	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A11	000000


				1-64	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A12	000000
				1-72	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A13	000000
				2-56	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A14	000000
				2-64	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A15	000000
				3-48	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A16	000000
				3-56	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A61	000000
				4-40	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A17	000000
				4-48	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A18	000000
				5-40	UNC	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A19	000000
				5-44	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A62	000000


				6-32	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A21	000000
				6-40	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A22	000000
				8-32	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A23	000000
				8-36	UNF	-0.0002" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A24	000000
				10-24	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A25	000000
				10-32	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A26	000000
				12-24	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A27	000000
				12-28	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A28	000000
				12-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A63	000000
				1/4"-20	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A29	000000


				1/4"-28	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A31	000000
				1/4"-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A64	000000
				5/16"-18	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A32	000000
				5/16"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A33	000000
				5/16"-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A65	000000
				3/8"-16	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A34	000000
		3/8"-24		UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A35	000000
		3/8"-32	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A66	000000
		7/16"-14	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A36	000000
		7/16"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A37	000000


		7/16"-28	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A67	000000
		1/2"-13	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A38	000000
		1/2"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A39	000000
		1/2"-28	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A68	000000
		9/16"-18	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A41	000000
		9/16"-24	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A69	000000
		5/8"-11	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A42	000000
		5/8"-18	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A43	000000
		5/8"-24	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A71	000000
		11/16"-24	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A72	000000


		3/4"-10	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A44	000000
		3/4"-16	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A45	000000
		3/4"-20	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A73	000000
		7/8"-9	UNC	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A46	000000
		7/8"-14	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A47	000000
		7/8"-20	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A74	000000
		1"-8	UNC	-0.0004" to 0.0004"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A48	000000
		1"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A49	000000
		1"-14	UNS	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A75	000000
		1"-20	UNEF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A76	000000

1 1/8"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A51	000000
1 1/4"-7	UNC	-0.0004" to 0.0004"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A52	000000
1 1/4"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A53	000000
1 3/8"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A77	000000
1 1/2"-6	UNC	-0.0004" to 0.0004"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A54	000000
1 1/2"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	3157A55	000000

Threaded Plug Gauges

Test if internal threads fall within tolerance. These plug gauges are often used in nuts and tapped holes to confirm thread fit. For precision and accuracy, they’re manufactured to tight tolerances.

Threads are within tolerance if it’s easy to thread a go gauge but difficult to thread a no-go gauge more than two turns.

Class X Gauge

Go Gauge—Go gauges check the minimum hole diameter.

No-Go Gauge—No-go gauges check the maximum hole diameter.

For Class 2B Unified Standard Thread Fit—For inch threads, the higher the class number, the tighter the fit. Unified Standard Class 2B is standard and works for most applications.

For Thread Fit—Thread fit designates the tightness or looseness of mating threads.

	Thread Size	Thread Type	Pitch Dia. Tolerance	Hardness	Material	For Thread Fit		Each
Go Gauges



		0-80	UNF	0" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N11	000000


		2-56	UNC	0" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N12	00000
		4-40	UNC	0" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N13	00000
		6-32	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N14	00000
		8-32	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N15	00000
		10-24	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N16	00000
		10-32	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N17	00000
		1/4"-20	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N18	00000
		1/4"-28	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N19	00000
		5/16"-18	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N21	00000
		5/16"-24	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N22	00000


		3/8"-16	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N23	00000
		3/8"-24	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N24	00000
		7/16"-20	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N25	00000
		1/2"-13	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N26	00000
		1/2"-20	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N27	00000
		9/16"-18	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N28	00000
		5/8"-11	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N29	00000
		5/8"-18	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N31	00000
		3/4"-10	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N32	00000
		3/4"-16	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N33	00000


		Go Gauges with Accuracy Certificate Traceable to NIST



				0-80	UNF	0" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N101	00000


				2-56	UNC	0" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N102	00000
				4-40	UNC	0" to 0.0002"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N103	00000
				6-32	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N104	00000
				8-32	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N105	00000
				10-24	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N106	00000
				10-32	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N107	00000
				1/4"-20	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N108	00000
				1/4"-28	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N109	00000
				5/16"-18	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N111	00000
				5/16"-24	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N112	00000


				3/8"-16	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N113	00000
				3/8"-24	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N114	00000
				7/16"-20	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N115	00000
				1/2"-13	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N116	00000
				1/2"-20	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N117	00000
				9/16"-18	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N118	00000
				5/8"-11	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N119	00000
				5/8"-18	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N121	00000
				3/4"-10	UNC	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N122	00000
				3/4"-16	UNF	0" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 2B, Unified Standard Class 3B	7968N123	00000


				No-Go Gauges



0-80	UNF					-0.0002" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N45	00000


10-32	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N53	00000
1/4"-28	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N56	00000
5/16"-24	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N59	00000
3/8"-24	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N63	00000
7/16"-20	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N65	00000
1/2"-20	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N68	00000
9/16"-18	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N71	00000
5/8"-18	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N74	00000
3/4"-16	UNF					-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N77	00000


No-Go Gauges with Accuracy Certificate Traceable to NIST



						0-80	UNF	-0.0002" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N135	00000


						10-32	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N143	00000
						1/4"-28	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N146	00000
						5/16"-24	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N149	00000
						3/8"-24	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N153	00000
						7/16"-20	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N155	00000
						1/2"-20	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N158	00000
						9/16"-18	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N161	00000
						5/8"-18	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N164	00000
						3/4"-16	UNF	-0.0003" to 0"	Rockwell C70	Chrome-Plated Tool Steel	Unified Standard Class 3B	7968N167	00000

Go/No-Go Left-Hand Threaded Plug Gauges with Handle

A go and no-go gauge in one, these gauges check that left-hand threads fall within tolerance. Use them to confirm thread fit for nuts, tapped holes, and other parts. The taperlock handle speeds up tests, giving you a good grip to thread and unthread each gauge end. It also lets you swap out worn gauges for new ones (not included) on either end.

The go gauge checks the minimum internal thread size, and the no-go gauge checks the maximum. A part is within tolerance if it’s easy to thread the go gauge but difficult to thread the no-go gauge more than two turns.

Class X Gauge

Plug Gauges with Accuracy Certificate Traceable to NIST—Gauges with an accuracy certificate traceable to NIST include verification from the manufacturer that their thread sizes are within tolerance. The certificate is also known as a certificate of compliance or a short-form certification.

Plug Gauges with Calibration Certificate Traceable to NIST—Gauges with a calibration certificate traceable to NIST were calibrated in a lab. The certificate, sometimes called a test report or long-form certificate, details the tested measurements.

For Thread Fit—Thread fit designates the tightness or looseness of mating threads.

	Thread Type	Pitch Dia. Tolerance	Hardness	Material	Features	For Thread Fit		Each
Plug Gauges with Accuracy Certificate Traceable to NIST



	10-32	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N101	0000000


	1/4"-28	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N102	000000
	5/16"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N103	000000
	3/8"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N104	000000
	7/16"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N105	000000
	1/2"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N106	000000
	5/8"-18	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N107	000000
	3/4"-16	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N108	000000
	1 1/4"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7935N109	000000


	Plug Gauges with Calibration Certificate Traceable to NIST



			10-32	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N101	000000


			1/4"-28	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N102	000000
			5/16"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N103	000000
			3/8"-24	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N104	000000
			7/16"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N105	000000
			1/2"-20	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N106	000000
			5/8"-18	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N107	000000
			3/4"-16	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N108	000000
			1 1/4"-12	UNF	-0.0003" to 0.0003"	Rockwell C70	Chrome-Plated Tool Steel	Double-Ended Taperlock Handle	Unified Standard Class 3B	7938N109	000000