A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6130-01-474-5985
NSN 5855-00-361-0167
NSN 6130-01-631-8145
NSN 6645-00-780-5260
NSN 4140-01-169-2534
NSN 5935-01-136-1343
NSN 6105-01-557-4372
NSN 5990-01-193-0487
NSN 5835-00-104-8944
NSN 5950-01-211-7018
NSN 5975-00-156-5737
NSN 6220-01-444-4261