Also known as castle nuts, secure these nuts by inserting a cotter pin or safety wire through the slots and a drilled hole in your bolt for mild loosening resistance.

About half the strength of medium-strength steel locknuts, these are for light duty fastening applications, such as securing access panels.

With a slim, round profile and a slotted drive, these metric nuts work in tight spots where there's no room for a wrench to turn. Instead, tighten them from the center of the nut with a slotted screwdriver.

Attach these slip-on nuts at any point on a threaded rod for quick installation.