A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-01-092-1098
NSN 5925-00-718-7530
NSN 5998-00-050-2072
NSN 5960-01-129-4203
NSN 6240-01-643-4535
NSN 5960-01-276-7836
NSN 5960-01-541-9884
NSN 5985-00-195-9425
NSN 6130-00-567-9424
NSN 4140-01-572-6390
NSN 6150-00-395-9999
NSN 5895-01-205-3259