High Locknuts | McMaster-Carr

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49 Products

High-Profile Nylon-Insert Locknuts

Slightly taller than standard-profile locknuts, these have a larger gripping area so your wrench or socket won't slip off as you tighten them. They're often used in vehicles and machinery where fasteners can be difficult to reach. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.

High-Strength Steel

Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd., mm	Ht., mm	Fastener Strength Grade/Class	Insert Max. Temp., ° F	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	M6 × 1 mm	10	8	ISO Class 10	220	DIN 982	50	000000000	000000


	M8 × 1.25 mm	13	9.5	ISO Class 10	220	DIN 982	25	000000000	0000
	M10 × 1.5 mm	17	11.5	ISO Class 10	220	DIN 982	25	000000000	00000
	M12 × 1.75 mm	19	14	ISO Class 10	220	DIN 982	10	000000000	00000
	M14 × 2 mm	22	16	ISO Class 10	220	DIN 982	10	000000000	00000
	M16 × 2 mm	24	18	ISO Class 10	220	DIN 982	5	000000000	00000
	M18 × 2.5 mm	27	20	ISO Class 10	220	DIN 982	5	000000000	00000
	M20 × 2.5 mm	30	22	ISO Class 10	220	DIN 982	1	000000000	0000
	M24 × 3 mm	36	28	ISO Class 10	220	DIN 982	1	000000000	0000

Medium-Strength Steel

These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Yellow-Chromate-Plated Steel—With a more durable finish than clear zinc plating, these nuts are suitable for most wet and outdoor environments. However, they won't hold up to the harsh chemicals that stainless steel can.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd., mm	Ht., mm	Fastener Strength Grade/Class	Insert Max. Temp., ° F	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Yellow-Chromate-Plated Steel



	M5 × 0.8 mm	8	6.3	ISO Class 8	220	DIN 982, ISO 7040	100	000000000	00000


	M6 × 1 mm	10	8	ISO Class 8	220	DIN 982, ISO 7040	100	000000000	00000
	M8 × 1.25 mm	13	9.5	ISO Class 8	220	DIN 982, ISO 7040	100	000000000	00000
	M10 × 1.5 mm	17	11.5	ISO Class 8	220	DIN 982, ISO 7040	50	000000000	00000
	M12 × 1.75 mm	19	14	ISO Class 8	220	DIN 982, ISO 7040	25	000000000	00000
	M16 × 2 mm	24	18	ISO Class 8	220	DIN 982, ISO 7040	10	000000000	0000
	M20 × 2.5 mm	32	22	ISO Class 8	220	DIN 982, ISO 7040	5	000000000	00000
	M24 × 3 mm	36	28	ISO Class 8	220	DIN 982, ISO 7040	1	000000000	0000


	Zinc-Plated Steel



			M4 × 0.7 mm	7	5.3	ISO Class 8	220	DIN 982, ISO 7040	100	000000000	0000


			M5 × 0.8 mm	8	6.3	ISO Class 8	220	DIN 982, ISO 7040	100	000000000	0000
			M6 × 1 mm	10	8	ISO Class 8	220	DIN 982, ISO 7040	100	000000000	00000
			M8 × 1.25 mm	13	9.5	ISO Class 8	220	DIN 982, ISO 7040	50	000000000	00000
			M10 × 1.5 mm	17	11.5	ISO Class 8	220	DIN 982, ISO 7040	25	000000000	00000
			M12 × 1.75 mm	19	14	ISO Class 8	220	DIN 982, ISO 7040	25	000000000	00000
			M14 × 1.5 mm	22	16	ISO Class 8	220	DIN 982, ISO 7040	10	000000000	00000
			M14 × 2 mm	22	16	ISO Class 8	220	DIN 982, ISO 7040	10	000000000	00000
			M16 × 1.5 mm	24	18	ISO Class 8	220	DIN 982, ISO 7040	5	000000000	00000
			M16 × 2 mm	24	18	ISO Class 8	220	DIN 982, ISO 7040	10	000000000	00000
			M18 × 2.5 mm	27	20	ISO Class 8	220	DIN 982, ISO 7040	5	000000000	00000


			M20 × 1.5 mm	30	22	ISO Class 8	220	DIN 982, ISO 7040	1	000000000	0000
			M20 × 2.5 mm	30	22	ISO Class 8	220	DIN 982, ISO 7040	1	000000000	0000
			M22 × 2.5 mm	32	25	ISO Class 8	220	DIN 982, ISO 7040	1	000000000	0000
			M24 × 3 mm	36	28	ISO Class 8	220	DIN 982, ISO 7040	1	000000000	0000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

316 Stainless Steel—Our most corrosion-resistant nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.

	Wd., mm	Ht., mm	Insert Max. Temp., ° F	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	M4 × 0.7 mm	7	5.3	220	DIN 982	25	000000000	00000


	M5 × 0.8 mm	8	6.3	220	DIN 982	25	000000000	0000
	M6 × 1 mm	10	8	220	DIN 982	25	000000000	0000
	M8 × 1.25 mm	13	9.5	220	DIN 982	10	000000000	0000
	M10 × 1.5 mm	17	11.5	220	DIN 982	10	000000000	00000
	M12 × 1.75 mm	19	14	220	DIN 982	5	000000000	0000
	M16 × 2 mm	24	18	220	DIN 982	1	000000000	0000
	M20 × 2.5 mm	30	22	220	DIN 982	1	000000000	0000


	316 Stainless Steel



			M4 × 0.7 mm	7	5.3	220	DIN 982	10	000000000	0000


			M5 × 0.8 mm	8	6.3	220	DIN 982	10	000000000	0000
			M6 × 1 mm	10	8	220	DIN 982	10	000000000	0000
			M8 × 1.25 mm	13	9.5	220	DIN 982	10	000000000	0000
			M10 × 1.5 mm	17	11.5	220	DIN 982	5	000000000	0000
			M12 × 1.75 mm	19	14	220	DIN 982	5	000000000	00000
			M16 × 2 mm	24	18	220	DIN 982	1	000000000	0000
			M20 × 2.5 mm	30	22	220	DIN 982	1	000000000	0000
			M24 × 3 mm	36	28	220	DIN 982	1	000000000	00000