A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 7035-00-455-7666
NSN 6220-01-016-7112
NSN 5935-00-391-6275
NSN 5998-01-531-4847
NSN 6220-00-412-2741
NSN 6130-01-375-5498
NSN 6105-01-251-6824
NSN 6645-01-503-2240
NSN 6320-00-456-0836
NSN 6620-01-068-4498
NSN 5945-00-281-1351
NSN 5975-00-268-3818