A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5920-00-245-6434
NSN 6610-01-592-1551
NSN 6130-01-283-8822
NSN 5975-00-935-9617
NSN 5975-01-623-8901
NSN 5925-01-562-6277
NSN 5975-01-418-2527
NSN 6150-00-994-5030
NSN 6320-01-388-1067
NSN 5925-00-932-0108
NSN 6110-01-550-9762
NSN 6620-01-532-4147