Often referred to as castle nuts, secure these by inserting a cotter pin or safety wire through the slots and a drilled hole in your bolt for mild loosening resistance. They’re not recommended for use on parts exposed to high vibration because the pin is prone to shearing under prolonged stress. Height includes the slots. Cotter pins are not included.

Zinc-plated steel locknuts resist corrosion in wet environments.

Steel locknuts are best for dry environments, since moisture will cause them to rust. They are weldable and can be painted or finished.

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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.

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These nuts are designed to secure ASTM A325 bolts in structural joints. Also known as heavy hex nuts, they are about 10% wider and taller than standard hex nuts and distribute the load over a large area.

Steel nuts without a finish are weldable and ready to be painted or finished.

Black-oxide steel nuts have a dark surface color and are mildly corrosion resistant in dry environments.

Hot-dipped galvanized steel nuts have a thick coating for good corrosion resistance. They must be used with other hot-dipped galvanized fasteners.

For technical drawings and 3-D models, click on a part number.