A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-00-194-4252
NSN 5935-01-589-0937
NSN 5895-01-328-9094
NSN 5915-01-221-8135
NSN 5905-01-508-1339
NSN 5905-00-166-0358
NSN 5999-00-674-9478
NSN 6650-01-415-5573
NSN 5835-01-537-1228
NSN 5855-01-416-0084
NSN 5965-01-238-3900
NSN 6650-01-329-8020