A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-00-567-9291
NSN 5925-01-073-9736
NSN 5935-00-683-2939
NSN 6650-00-045-4362
NSN 5895-01-156-4252
NSN 6645-00-116-1409
NSN 6320-01-643-0850
NSN 5930-01-382-4926
NSN 5996-00-333-5182
NSN 6320-01-054-3046
NSN 6650-01-614-0947
NSN 6610-01-102-0194