Round-Top Square Nuts | McMaster-Carr

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105 Products

Low-Strength Steel Square Nuts

Large flat sides make these nuts easy to grip with a wrench and keep them from rotating in channels and square holes. About half the strength of medium-strength steel square nuts, use them in light duty fastening applications, such as securing access panels.

Black-Zinc-Plated Steel—Black-zinc-plated steel square nuts resist corrosion in wet environments and have a black finish that blends in with dark surfaces.

Hot-Dipped Galvanized Steel—Hot-dipped galvanized steel square nuts have a thick coating for better corrosion resistance than zinc-plated steel nuts. They must be used with other hot-dipped galvanized fasteners.

Steel—Steel square nuts are best for dry environments, since moisture will cause them to rust.

Zinc-Plated Steel—Zinc-plated steel square nuts resist corrosion in wet environments.

	Thread Size	Wd.	Ht.	Specs. Met	Pkg. Qty.		Pkg.
Hot-Dipped Galvanized Steel



		5/16"-18	9/16"	17/64"	—	100	93430A410	000000
		3/8"-16	5/8"	21/64"	—	100	93430A415	00000
		1/2"-13	13/16"	7/16"	—	50	93430A421	00000
		5/8"-11	1"	35/64"	—	25	93430A425	00000
		3/4"-10	1 1/8"	21/32"	—	10	93430A430	0000
		7/8"-9	1 5/16"	49/64"	—	5	93430A435	0000
		1"-8	1 1/2"	7/8"	—	5	93430A440	00000


		Steel



				1/4"-20	7/16"	7/32"	—	100	90043A029	0000
				5/16"-18	9/16"	17/64"	—	100	90043A030	00000
				3/8"-16	5/8"	21/64"	—	100	90043A031	00000
				7/16"-14	3/4"	3/8"	—	25	90043A034	00000
				1/2"-13	13/16"	7/16"	—	50	90043A055	00000
				5/8"-11	1"	35/64"	—	25	90043A065	00000
				3/4"-10	1 1/8"	21/32"	—	10	90043A075	00000
				7/8"-9	1 5/16"	49/64"	—	5	90043A085	00000
				1"-8	1 1/2"	7/8"	—	5	90043A095	00000
				1 1/8"-7	1 11/16"	1"	—	1	90043A105	0000


				1 1/4"-7	1 7/8"	1 3/32"	—	1	90043A115	0000
				1 1/2"-6	2 1/4"	1 5/16"	—	1	90043A125	0000


				Steel—ISO Class 5



						M4 × 0.7 mm	7 mm	3 mm	DIN 557	50	96887A111	0000
						M5 × 0.8 mm	8 mm	4 mm	DIN 557	50	96887A112	00000
						M6 × 1 mm	10 mm	5 mm	DIN 557	25	96887A113	0000
						M8 × 1.25 mm	13 mm	6.5 mm	DIN 557	25	96887A114	0000
						M10 × 1.5 mm	17 mm	8 mm	DIN 557	10	96887A115	0000
						M12 × 1.75 mm	19 mm	10 mm	DIN 557	5	96887A116	0000


						Zinc-Plated Steel—ISO Class 5



								M4 × 0.7 mm	7 mm	3.2 mm	DIN 557	100	96887A329	00000
								M5 × 0.8 mm	8 mm	4 mm	DIN 557	100	96887A331	00000
								M6 × 1 mm	10 mm	5 mm	DIN 557	100	96887A319	00000
								M8 × 1.25 mm	13 mm	6.5 mm	DIN 557	25	96887A322	0000
								M10 × 1.5 mm	17 mm	8 mm	DIN 557	25	96887A325	00000
								M12 × 1.75 mm	19 mm	10 mm	DIN 557	10	96887A328	0000
								M16 × 2 mm	24 mm	13 mm	DIN 557	5	96887A332	00000
								M20 × 2.5 mm	30 mm	16 mm	DIN 557	5	96887A334	00000


								Black-Zinc-Plated Steel—ISO Class 5



										M4 × 0.7 mm	7 mm	3 mm	DIN 557	25	96887A118	0000
										M5 × 0.8 mm	8 mm	4 mm	DIN 557	25	96887A119	0000
M6 × 1 mm										10 mm	5 mm	DIN 557	25	96887A121	0000
M8 × 1.25 mm	13 mm									6.5 mm	DIN 557	10	96887A122	0000
M10 × 1.5 mm	17 mm									8 mm	DIN 557	10	96887A123	00000
M16 × 2 mm	24 mm									13 mm	DIN 557	1	96887A125	0000

Fiberglass Square Nuts

These fiberglass square nuts are chemical resistant, nonconductive, and lightweight. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Max. Temp.	Color	Pkg. Qty.		Pkg.
Fiberglass



	3/8"-16	3/4"	17/32"	Not Rated	Gray	1	91332A031	00000
	1/2"-13	7/8"	41/64"	Not Rated	Gray	1	91332A033	0000
	5/8"-11	1 1/8"	51/64"	Not Rated	Gray	1	91332A035	0000
	3/4"-10	1 1/4"	57/64"	Not Rated	Gray	1	91332A036	0000
	1"-8	1 11/16"	1 9/64"	Not Rated	Gray	1	91332A038	00000

Super-Corrosion-Resistant 316 Stainless Steel Square Nuts

These square nuts have excellent resistance to chemicals and salt water. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Pkg. Qty.		Pkg.
316 Stainless Steel



	1/4"-20	7/16"	3/16"	25	92891A100	000000
	5/16"-18	9/16"	7/32"	10	92891A200	0000
	3/8"-16	5/8"	1/4"	10	92891A300	00000
	1/2"-13	13/16"	7/16"	1	92891A400	0000
	5/8"-11	1"	35/64"	1	92891A102	0000
	3/4"-10	1 1/8"	21/32"	1	92891A103	00000

Brass Square Nuts

These square nuts are corrosion resistant in wet environments, electrically conductive, and nonmagnetic. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Brass



	4-40	1/4"	3/32"	100	90509A029	00000
	6-32	5/16"	7/64"	100	90509A030	00000
	8-32	11/32"	1/8"	50	90509A031	0000
	10-24	3/8"	1/8"	50	90509A032	00000
	10-32	3/8"	1/8"	50	90509A033	00000
	1/4"-20	7/16"	3/16"	25	90509A034	00000
	5/16"-18	9/16"	7/32"	10	90509A035	0000
	3/8"-16	5/8"	1/4"	10	90509A036	00000
	1/2"-13	13/16"	7/16"	5	90509A037	00000

Medium-Strength Steel Square Nuts

Large flat sides make these nuts easy to grip with a wrench and keep them from rotating in channels and square holes. Made from SAE Grade 5 steel, they're suitable for fastening most machinery and equipment.

Steel—Steel square nuts are best for dry environments, since moisture will cause them to rust.

Zinc-Plated Steel—Zinc-plated steel square nuts resist corrosion in wet environments.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Steel—SAE Grade 5



	1/4"-20	7/16"	7/32"	100	98694A211	00000
	5/16"-18	9/16"	17/64"	50	98694A212	0000
	3/8"-16	5/8"	21/64"	25	98694A213	0000
	7/16"-14	3/4"	3/8"	10	98694A214	0000
	1/2"-13	13/16"	7/16"	10	98694A215	0000
	5/8"-11	1"	35/64"	5	98694A216	0000
	3/4"-10	1 1/8"	21/32"	5	98694A217	0000
	7/8"-9	1 5/16"	49/64"	1	98694A218	0000
	1"-8	1 1/2"	7/8"	1	98694A219	0000
	1 1/4"-7	1 7/8"	1 3/32"	1	98694A221	0000


	Zinc-Plated Steel—SAE Grade 5



			1/4"-20	7/16"	7/32"	100	98694A110	0000
			5/16"-18	9/16"	17/64"	100	98694A115	00000
			3/8"-16	5/8"	21/64"	50	98694A120	00000
			7/16"-14	3/4"	3/8"	25	98694A125	00000
			1/2"-13	13/16"	7/16"	25	98694A130	00000
			5/8"-11	1"	35/64"	10	98694A135	0000
			3/4"-10	1 1/8"	21/32"	10	98694A140	00000
			7/8"-9	1 5/16"	49/64"	5	98694A145	00000
			1"-8	1 1/2"	7/8"	1	98694A150	0000
			1 1/8"-7	1 11/16"	1"	1	98694A155	0000


			1 1/4"-7	1 7/8"	1 3/32"	1	98694A160	0000
			1 1/2"-6	2 1/4"	1 5/16"	1	98694A165	00000

18-8 Stainless Steel Square Nuts

These square nuts have good chemical resistance and may be mildly magnetic. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	2-56	3/16"	1/16"	—	100	94785A509	000000
	4-40	1/4"	3/32"	—	100	94785A511	00000
	6-32	5/16"	7/64"	—	100	94785A007	00000
	8-32	11/32"	1/8"	—	100	94785A009	00000
	10-24	3/8"	1/8"	—	100	94785A013	00000
	10-32	3/8"	1/8"	—	100	94785A411	00000
	1/4"-20	7/16"	3/16"	—	50	94785A415	00000
	1/4"-28	7/16"	3/16"	—	25	94785A439	0000
	5/16"-18	9/16"	7/32"	—	25	94785A419	0000
	5/16"-24	9/16"	7/32"	—	10	94785A441	0000


	3/8"-16	5/8"	1/4"	—	25	94785A423	00000
	3/8"-24	5/8"	1/4"	—	10	94785A442	0000
	7/16"-14	3/4"	3/8"	—	5	94785A443	0000
	7/16"-20	3/4"	3/8"	—	5	94785A445	00000
	1/2"-13	13/16"	7/16"	—	5	94785A427	0000
	5/8"-11	1"	35/64"	—	1	94785A431	0000
	3/4"-10	1 1/8"	21/32"	—	1	94785A435	0000
	1"-8	1 1/2"	7/8"	—	1	94785A438	00000
	M5 × 0.8 mm	8 mm	4 mm	DIN 557	50	90225A101	0000
	M6 × 1 mm	10 mm	5 mm	DIN 557	50	90225A102	00000


	M8 × 1.25 mm	13 mm	6.5 mm	DIN 557	25	90225A103	00000
	M10 × 1.5 mm	17 mm	8 mm	DIN 557	10	90225A104	0000
	M12 × 1.75 mm	19 mm	10 mm	DIN 557	5	90225A105	00000
	M16 × 2 mm	24 mm	13 mm	DIN 557	1	90225A106	00000