A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-029-2196
NSN 6240-01-179-4547
NSN 5945-01-296-0864
NSN 5915-00-965-0535
NSN 5945-01-649-3349
NSN 5855-00-149-0766
NSN 6110-00-824-5764
NSN 6150-00-596-9882
NSN 5985-01-019-9220
NSN 5996-00-467-4196
NSN 5935-01-089-7920
NSN 5895-01-456-6720