A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5835-01-565-3411
NSN 4140-01-612-6182
NSN 6645-01-440-8624
NSN 6220-00-148-8541
NSN 5925-01-195-8068
NSN 5835-01-416-6455
NSN 5998-01-578-7052
NSN 6620-00-826-7238
NSN 5925-00-436-3454
NSN 5998-00-315-3595
NSN 5985-00-338-6424
NSN 5895-00-827-7420