A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5999-01-162-4698
NSN 5915-01-252-8683
NSN 5950-01-426-3182
NSN 5960-00-549-3760
NSN 6645-00-155-2398
NSN 5855-01-534-3724
NSN 5935-01-129-0084
NSN 5935-01-407-4191
NSN 6240-00-116-7442
NSN 6650-01-462-0830
NSN 5920-00-453-4377
NSN 5999-00-153-4175