A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-573-6490
NSN 5950-00-729-8839
NSN 5925-01-325-8920
NSN 5920-00-089-8006
NSN 6610-01-282-9953
NSN 4140-01-228-6543
NSN 6320-00-456-2092
NSN 5960-01-491-9916
NSN 6220-01-640-6930
NSN 6650-01-456-1225
NSN 5990-01-178-6307
NSN 5990-00-682-3531