A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6220-00-202-8591
NSN 5910-00-312-4433
NSN 6220-00-583-3442
NSN 5975-01-436-2767
NSN 6650-01-367-4989
NSN 5999-00-529-0157
NSN 5910-00-592-1181
NSN 4140-00-079-8453
NSN 5895-01-316-6101
NSN 7035-01-400-3666
NSN 5920-01-142-7554
NSN 6620-00-703-4260