A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5998-00-007-1977
NSN 5950-01-630-0597
NSN 5999-01-424-2950
NSN 4140-01-028-9602
NSN 5920-01-618-7527
NSN 6650-01-090-0099
NSN 5960-00-275-7497
NSN 5855-01-428-9456
NSN 6240-01-646-0860
NSN 5950-00-473-8683
NSN 5905-01-485-0234
NSN 6240-01-165-2693