A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-01-442-5155
NSN 5990-01-176-9731
NSN 6240-00-792-5469
NSN 6620-01-632-2154
NSN 6685-01-441-1846
NSN 7035-01-578-8449
NSN 6110-00-031-7299
NSN 6240-00-269-3346
NSN 5920-00-127-8098
NSN 5915-01-602-5164
NSN 5996-01-503-8589
NSN 5975-00-435-4198