A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-607-1491
NSN 5999-01-425-1377
NSN 6610-00-854-9166
NSN 5945-01-032-4731
NSN 5950-00-416-8282
NSN 6145-01-588-2847
NSN 5925-01-037-6621
NSN 5999-01-144-2610
NSN 5925-00-115-8114
NSN 6105-01-358-4032
NSN 6110-01-533-3862
NSN 6650-01-466-2704