A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-228-7420
NSN 6145-01-228-5231
NSN 6610-01-643-6652
NSN 5999-00-922-1442
NSN 5835-01-408-7576
NSN 6650-00-573-7131
NSN 5855-00-357-1158
NSN 6240-00-155-7836
NSN 5935-01-211-6986
NSN 5990-00-927-9751
NSN 5915-01-614-0980
NSN 5990-01-054-4255