A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6150-00-769-5017
NSN 4140-00-912-1904
NSN 5930-01-513-3933
NSN 6150-01-428-7071
NSN 5965-00-133-3031
NSN 5950-01-047-1345
NSN 6320-01-357-3222
NSN 6620-01-026-0346
NSN 5996-01-141-5435
NSN 6620-01-345-1336
NSN 6240-01-366-5538
NSN 5999-00-618-9701