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.

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

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