Two Way Reversible Hex Lock Nut Black Zinc and Wax
This is the least expensive prevailing torque type of nut, designed for use with machine screws and low-carbon bolts (or 18-8 screws with the stainless nuts). It allows for automatic assembly because the top and bottom of the nut are identical. It creates a locking action even without being fully threaded onto its mating screw.
