A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5905-01-179-9433
NSN 6150-01-108-4168
NSN 4140-01-400-3610
NSN 6685-01-050-9478
NSN 6130-01-390-7031
NSN 5950-01-023-2247
NSN 6650-01-302-7684
NSN 6220-00-643-4045
NSN 6110-01-314-8429
NSN 6610-00-138-0740
NSN 6105-01-423-7008
NSN 6645-01-658-3187