System of Measurement System of Measurement |
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Thread Size Thread Size |
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Nut Type Nut Type | Show |
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Specifications Met Specifications Met |
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Locking Type Locking Type |
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Nylon Insert | Distorted Thread |
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Flex-Top |
Height Height |
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Material Material |
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Finish Finish | Show |
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Finish Finish | Hide |
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Thread Direction Thread Direction |
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Drive Style Drive Style |
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DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense AcquisitionRegulations Supplement) |
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Insert Maximum Temperature Insert Maximum Temperature |
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Press-Fit Head Shape Press-Fit Head Shape |
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For Minimum Panel Thickness For Minimum Panel Thickness |
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About Nuts, Materials, and Finishes
More
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 |
6-32 | 5/16" | 3/16" | 250° | MS21044-N06 | 10 | 000000000 | 0000 |
8-32 | 11/32" | 9/32" | 250° | MS21044-N08 | 10 | 000000000 | 0000 |
10-32 | 3/8" | 9/32" | 250° | MS21044-N3 | 10 | 000000000 | 0000 |
1/4"-28 | 7/16" | 23/64" | 250° | MS21044-N4 | 10 | 000000000 | 0000 |
5/16"-24 | 1/2" | 23/64" | 250° | MS21044-N5 | 5 | 000000000 | 00000 |
3/8"-24 | 9/16" | 15/32" | 250° | MS21044-N6 | 5 | 000000000 | 00000 |
1/2"-20 | 3/4" | 19/32" | 250° | MS21044-N8 | 5 | 000000000 | 0000 |
5/8"-18 | 15/16" | 3/4" | 250° | MS21044-N10 | 1 | 000000000 | 0000 |
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 |
6-32 | 5/16" | 9/64" | 250° | MS21083N06, NASM21083 | 10 | 000000000 | 00000 |
8-32 | 11/32" | 3/16" | 250° | MS21083N08, NASM21083 | 10 | 000000000 | 0000 |
10-32 | 3/8" | 3/16" | 250° | MS21083N3, NASM21083 | 10 | 000000000 | 0000 |
1/4"-28 | 7/16" | 7/32" | 250° | MS21083N4, NASM21083 | 10 | 000000000 | 0000 |
1/2"-20 | 3/4" | 5/16" | 250° | MS21083N8, NASM21083 | 1 | 000000000 | 0000 |
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 |
6-32 | 5/16" | 3/16" | MS21045-06 | 5 | 000000000 | 0000 |
8-32 | 11/32" | 1/4" | MS21045-08 | 5 | 000000000 | 00000 |
10-32 | 3/8" | 1/4" | MS21045-3 | 5 | 000000000 | 0000 |
1/4"-28 | 7/16" | 5/16" | MS21045-4 | 5 | 000000000 | 00000 |
5/16"-24 | 1/2" | 23/64" | MS21045-5 | 5 | 000000000 | 00000 |
3/8"-24 | 9/16" | 15/32" | MS21045-6 | 5 | 000000000 | 00000 |
7/16"-20 | 11/16" | 15/32" | MS21045-7 | 1 | 000000000 | 00000 |
1/2"-20 | 3/4" | 39/64" | MS21045-8 | 1 | 000000000 | 00000 |
9/16"-18 | 7/8" | 11/16" | MS21045-9 | 1 | 000000000 | 00000 |
5/8"-18 | 15/16" | 49/64" | MS21045-10 | 1 | 000000000 | 00000 |
3/4"-16 | 1 1/16" | 57/64" | MS21045-12 | 1 | 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.
Flange | Locknuts | Locknuts with Lubricant | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Thread Size | Wd. | Ht. | Dia. | Thick. | Pkg. Qty. | Specifications Met | Pkg. | Specifications Met | Pkg. | ||
Cadmium Yellow-Chromate Plated Steel | |||||||||||
2-56 | 1/8" | 3/32" | 0.167" | 0.01" | 5 | MS21042-02 | 000000000 | 00000 | MS21042L-02 | 000000000 | 000000 |
4-40 | 5/32" | 1/8" | 0.206" | 0.03" | 5 | MS21042-04 | 000000000 | 0000 | MS21042L-04 | 000000000 | 0000 |
6-32 | 3/16" | 9/64" | 0.244" | 0.03" | 5 | MS21042-06 | 000000000 | 0000 | MS21042L-06 | 000000000 | 0000 |
8-32 | 7/32" | 3/16" | 0.29" | 0.03" | 5 | MS21042-08 | 000000000 | 0000 | MS21042L-08 | 000000000 | 0000 |
10-32 | 1/4" | 3/16" | 0.33" | 0.03" | 5 | MS21042-3 | 000000000 | 0000 | MS21042L-3 | 000000000 | 0000 |
1/4"-28 | 5/16" | 7/32" | 0.42" | 0.04" | 5 | MS21042-4 | 000000000 | 0000 | MS21042L-4 | 000000000 | 0000 |
5/16"-24 | 3/8" | 17/64" | 0.52" | 0.04" | 1 | MS21042-5 | 000000000 | 0000 | MS21042L-5 | 000000000 | 0000 |
3/8"-24 | 7/16" | 9/32" | 0.62" | 0.04" | 1 | MS21042-6 | 000000000 | 0000 | MS21042L-6 | 000000000 | 0000 |
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.
Cadmium yellow-chromate plated steel locknuts resist corrosion in wet environments.
For technical drawings and 3-D models, click on a part number.