A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6145-00-596-8447
NSN 5990-00-446-0518
NSN 5835-00-498-1551
NSN 5975-01-120-1088
NSN 5905-01-184-4065
NSN 7035-00-054-3414
NSN 6150-01-612-9422
NSN 6620-00-932-4306
NSN 6320-01-498-4954
NSN 5910-00-099-9998
NSN 6650-00-256-9059
NSN 4140-01-098-0213