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Nylon Insert | Serrations |
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Distorted Thread | Lock Washer |
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REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration,Evaluation, Authorization and Restriction of Chemicals) |
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DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense AcquisitionRegulations Supplement) |
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About Nuts, Materials, and Finishes
More
Low-Strength Steel Nylon-Insert Locknuts

These locknuts have a nylon insert that grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use. About half the strength of medium-strength steel locknuts, they're for light duty fastening applications, such as securing access panels.
Zinc-plated steel locknuts are corrosion resistant in wet environments.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 9/64" | 220° | 100 | 000000000 | 00000 |
Mil. Spec. Low-Strength Steel Nylon-Insert Locknuts

Choose these locknuts for their adherence to strict military standards for material and construction. The nylon insert grips the bolt to resist loosening without damaging threads. These locknuts are reusable, but their holding power lessens with each use. A cadmium yellow-chromate plating provides corrosion resistance in wet environments and adds lubricity so they thread on smoothly.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Specifications Met | Pkg. Qty. | Pkg. | |
Cadmium Yellow-Chromate Plated Steel | |||||||
---|---|---|---|---|---|---|---|
4-40 | 1/4" | 5/32" | 250° | MS21044-N04 | 10 | 000000000 | 00000 |
18-8 Stainless Steel Nylon-Insert Locknuts

These locknuts have good chemical resistance and may be mildly magnetic. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
Black-oxide stainless steel nuts have a dark surface color.
For technical drawings and 3-D models, click on a part number.
Mil. Spec. 18-8 Stainless Steel Nylon-Insert Locknuts

Choose these locknuts for their adherence to strict military standards for material and construction. Made from 18-8 stainless steel, they have good chemical resistance and may be mildly magnetic. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Specifications Met | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | |||||||
---|---|---|---|---|---|---|---|
4-40 | 1/4" | 5/32" | 250° | MS21044C04, NASM21044 | 10 | 000000000 | 000000 |
Super-Corrosion-Resistant 316 Stainless Steel Nylon-Insert Locknuts

These locknuts have excellent resistance to chemicals and salt water. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use. They may be mildy magnetic.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Pkg. Qty. | Pkg. | |
316 Stainless Steel | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 9/64" | 220° | 100 | 000000000 | 00000 |
Brass Nylon-Insert Locknuts

These locknuts are corrosion resistant in wet environments, electrically conductive, and nonmagnetic. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Pkg. Qty. | Pkg. | |
Brass | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 9/64" | 220° | 50 | 000000000 | 00000 |
Titanium Nylon-Insert Locknuts

Titanium locknuts have a high strength-to-weight ratio, resist acids and salt water, and are nonmagnetic. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Pkg. Qty. | Pkg. | |
Grade 5 Titanium | |||||
---|---|---|---|---|---|
4-40 | 1/4" | 9/64" | 1 | 000000000 | 00000 |
Low-Strength Steel Thin Nylon-Insert Locknuts

These locknuts are about half the height of standard nylon-insert locknuts. Use them in light duty low-clearance applications or jam one against a hex nut to hold it in place. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
Zinc-plated steel locknuts resist corrosion in wet environments.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 7/64" | 220° | 100 | 000000000 | 00000 |
Mil. Spec. Low-Strength Steel Thin Nylon-Insert Locknuts

Choose these locknuts for their adherence to strict military standards for material and construction. About half the height of standard nylon-insert locknuts, use them in light duty low-clearance applications or jam one against a hex nut to hold it in place. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use. A cadmium yellow-chromate plating provides corrosion resistance in wet environments and adds lubricity so they thread on smoothly.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Specifications Met | Pkg. Qty. | Pkg. | |
Cadmium Yellow-Chromate Plated Steel | |||||||
---|---|---|---|---|---|---|---|
4-40 | 1/4" | 1/8" | 250° | MS21083N04, NASM21083 | 10 | 000000000 | 000000 |
18-8 Stainless Steel Thin Nylon-Insert Locknuts

These locknuts have good chemical resistance and may be mildly magnetic. They're about half the height of standard nylon-insert locknuts. Use them in low-clearance applications or jam one against a hex nut to hold it in place. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 7/64" | 220° | 50 | 000000000 | 00000 |
Mil. Spec. 18-8 Stainless Steel Thin Nylon-Insert Locknuts

Choose these locknuts for their adherence to strict military standards for material and construction. They have good chemical resistance and may be mildly magnetic. About half the height of standard nylon-insert locknuts, use them in low-clearance applications or jam one against a hex nut to hold it in place. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Insert Max. Temp., °F | Specifications Met | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | |||||||
---|---|---|---|---|---|---|---|
4-40 | 1/4" | 1/8" | 250° | MS21083C04, NASM21083 | 10 | 000000000 | 000000 |
Steel Locknuts with External-Tooth Lock Washer

Also known as Keps and K-Lock nuts, these locknuts have a free-spinning tooth lock washer that grips the material surface instead of threads for easy installation and mild vibration resistance. Height includes the thickness of the washer. A zinc plating provides corrosion resistance in wet environments.
For technical drawings and 3-D models, click on a part number.
Stainless Steel Locknuts with External-Tooth Lock Washer

These stainless steel locknuts have good chemical resistance and may be mildly magnetic. Also known as Keps and K-Lock nuts, they have a free-spinning tooth lock washer that grips the material surface instead of threads for easy installation and mild vibration resistance. Height includes the thickness of the washer.
For technical drawings and 3-D models, click on a part number.
Washer | |||||||
---|---|---|---|---|---|---|---|
Thread Size | Wd. | Ht. | Material | OD | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | |||||||
Standard Hex Nut Profile | |||||||
4-40 | 1/4" | 1/8" | 400 Stainless Steel | 0.281" | 100 | 000000000 | 00000 |
Steel Nonmarring Locknuts with Spring-Lock Washer

These locknuts have a curved washer that acts as a spring to add tension between the nut and the material surface for easy installation and mild vibration resistance. The smooth rim makes them less likely to scratch materials when tightened than locknuts with a tooth lock washer. Also known as Keps and K-lock nuts.
Black-oxide locknuts are mildly corrosion resistant and have a dark surface color.
Zinc-plated locknuts have an outer layer of zinc that provides corrosion resistance in wet environments.
For technical drawings and 3-D models, click on a part number.
Steel Flex-Top Locknuts for Heavy Vibration

Threads at the top of these locknuts expand to grip the bolt on all sides for a stronger hold than distorted-thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging the threads. These locknuts have equivalent strength to Grade 8 steel locknuts.
Cadmium-plated steel locknuts are corrosion resistant in wet environments. The plating adds lubricity, so they thread on smoothly.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Pkg. Qty. | Pkg. | |
Cadmium-Plated Steel | |||||
---|---|---|---|---|---|
4-40 | 1/4" | 5/32" | 25 | 000000000 | 000000 |
Mil. Spec. Steel Flex-Top Locknuts for Heavy Vibration

Choose these locknuts for their adherence to strict military standards for material and construction. Threads at the top of the nut expand to grip the bolt on all sides for a stronger hold than distorted-thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging threads. These locknuts have equivalent strength to Grade 8 steel locknuts. A cadmium yellow-chromate plating provides corrosion resistance in wet environments and adds lubricity so they thread on smoothly.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Specifications Met | Pkg. Qty. | Pkg. | |
Cadmium Yellow-Chromate Plated Steel | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 5/32" | MS21045-04 | 5 | 000000000 | 000000 |
Stainless Steel Flex-Top Locknuts for Heavy Vibration

These locknuts have good chemical resistance and may be mildly magnetic. Threads at the top of the nut expand to grip the bolt on all sides for a stronger hold than distorted-thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging threads.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | |||||
---|---|---|---|---|---|
4-40 | 1/4" | 5/32" | 5 | 000000000 | 000000 |
Mil. Spec. Stainless Steel Flex-Top Locknuts for Heavy Vibration

Choose these locknuts for their adherence to strict military standards for material and construction. Made from 18-8 stainless steel, they have good chemical resistance and may be mildly magnetic. Threads at the top of the nut expand to grip the bolt on all sides for a stronger hold than distorted-thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging threads. A silver plating adds lubricity so they thread on smoothly.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Specifications Met | Pkg. Qty. | Pkg. | |
Silver-Plated 18-8 Stainless Steel | ||||||
---|---|---|---|---|---|---|
4-40 | 1/4" | 9/64" | MS21046C04, NASM21046 | 1 | 000000000 | 000000 |
Low-Strength Steel Serrated Flange Locknuts

Serrations grip the material surface instead of the threads for easy installation and mild vibration resistance. The flange distributes pressure where the nut meets the material surface, eliminating the need for a separate washer. About half the strength of medium-strength steel flange locknuts, use them in light duty fastening applications, such as securing access panels. Height includes the flange.
Zinc-plated steel flange locknuts resist corrosion in wet environments.
For technical drawings and 3-D models, click on a part number.
Flange | |||||||
---|---|---|---|---|---|---|---|
Thread Size | Wd. | Ht. | Dia. | Thick. | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel | |||||||
4-40 | 1/4" | 5/32" | 25/64" | 0.02" | 25 | 000000000 | 00000 |
Mil. Spec. Low-Strength Steel Distorted-Thread Flange Locknuts

Choose these flange locknuts for their adherence to strict military standards for material and construction. They have an irregularly-shaped thread that grips the bolt for a stronger hold than nylon-insert flange locknuts. A flange that distributes pressure where the nut meets the material surface, eliminating the need for a separate washer. They're not reusable. A cadmium yellow-chromate plating provides corrosion resistance in wet environments. Height includes the flange.
Locknuts with lubricant keep screws from binding to the locknuts while you tighten them. They’re often used with screws made from soft metals, such as aluminum, which are more likely to bind to the locknuts than harder materials such as steel.
For technical drawings and 3-D models, click on a part number.
Stainless Steel Distorted-Thread Flange Locknuts

These flange locknuts have excellent resistance to chemicals and salt water. They have an irregularly shaped thread that grips the bolt for a stronger hold than nylon-insert flange locknuts. A flange distributes pressure where the nut meets the material surface, eliminating the need for a separate washer. These nuts may be mildly magnetic. Height includes the flange.
A286 stainless steel nuts cannot be reused. Those with lubricant thread onto bolts smoothly.
For technical drawings and 3-D models, click on a part number.
Thread-Forming Flange Locknuts

These nylon flange locknuts form threads as they're tightened to resist vibration. The flange distributes pressure where the nut meets the material surface, eliminating the need for a separate washer. They're not reusable. Made from nylon 6/6, they're chemical resistant, nonconductive, and lightweight. Height includes the flange.
For technical drawings and 3-D models, click on a part number.
Thread Size | Wd. | Ht. | Flange Dia. | Temp. Range, °F | Color | Pkg. Qty. | Pkg. | |
Nylon 6/6 Plastic | ||||||||
---|---|---|---|---|---|---|---|---|
4-40 | 1/4" | 3/16" | 1/4" | -40° to 185° | White | 100 | 000000000 | 000000 |
Distorted-Thread Cap Locknuts

An irregularly shaped thread grips the bolt for a stronger hold than nylon-insert cap locknuts. Also known as acorn locknuts, a smooth rounded head that covers and protects threads while providing a finished appearance. Made from 18-8 stainless steel, they have good chemical resistance.
For technical drawings and 3-D models, click on a part number.
Thread | ||||||
---|---|---|---|---|---|---|
Size | Dp. | Wd. | Ht. | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | ||||||
4-40 | 5/32" | 1/4" | 1/4" | 10 | 000000000 | 000000 |
Nylon-Insert Press-Fit Locknuts for Sheet Metal

These press-fit nuts have a nylon insert that grips threads to resist loosening and knurls on the bottom of the nut that hold them firmly in place. Press them into a drilled or punched hole with an installation tool or an arbor press. Installation requires access to both sides of the panel.
Steel locknuts without a finish are ready to be painted or finished.
18-8 stainless steel locknuts are chemical resistant and may be mildly magnetic.
For technical drawings and 3-D models, click on a part number.
Nylon-Insert Locknut Assortments


A nylon insert grips threads to resist loosening.
Zinc-plated steel locknuts are corrosion resistant in wet environments.
18-8 stainless steel locknuts are chemical resistant and may be mildly magnetic.
Assortments of Locknuts with External-Tooth Lock Washer


Teeth bite into surfaces for easy installation and mild vibration resistance.
Zinc-plated steel nuts are corrosion resistant in wet environments.
18-8 stainless steel nuts are chemical resistant and may be mildly magnetic.