A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5920-01-519-2321
NSN 6135-01-166-5042
NSN 6610-01-314-7964
NSN 4140-01-138-2228
NSN 6145-01-146-0954
NSN 6150-01-292-6990
NSN 6620-00-905-6590
NSN 6620-00-820-9616
NSN 5960-01-143-1202
NSN 5895-00-900-2381
NSN 5935-00-481-0940
NSN 5998-00-827-0527