A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6650-01-145-5173
NSN 5835-01-446-6065
NSN 5950-01-008-6948
NSN 6650-01-460-5837
NSN 5925-01-009-8976
NSN 6645-01-424-4667
NSN 5925-00-472-3444
NSN 6685-01-642-0597
NSN 6620-00-635-7347
NSN 6105-00-699-9186
NSN 5920-01-247-1389
NSN 5998-01-592-0166