A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6645-01-519-2220
NSN 5998-01-422-0624
NSN 5935-01-206-4368
NSN 6320-01-388-3125
NSN 5950-01-363-6328
NSN 4140-00-480-2592
NSN 5999-00-271-1681
NSN 6110-01-487-4039
NSN 5905-01-502-7028
NSN 5915-01-192-3224
NSN 5905-00-460-9787
NSN 5965-01-204-8505