A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5925-01-225-7757
NSN 5935-01-392-6056
NSN 5960-01-365-5729
NSN 5915-00-244-1702
NSN 6130-01-535-3101
NSN 5998-00-948-2011
NSN 6240-01-052-4248
NSN 5855-01-147-4785
NSN 6650-00-323-8150
NSN 6620-00-250-1980
NSN 6135-00-276-7625
NSN 5925-00-767-0284