A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6645-01-303-6792
NSN 6610-01-654-4685
NSN 6145-00-738-5601
NSN 5920-01-007-6165
NSN 6110-00-816-7444
NSN 5999-01-188-0230
NSN 5985-01-357-3919
NSN 7035-01-295-1609
NSN 5925-01-359-5532
NSN 6620-01-606-8964
NSN 5998-01-446-7514
NSN 6220-01-551-1681