A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-00-849-9940
NSN 5855-00-089-3974
NSN 5915-01-078-3516
NSN 5990-01-537-3972
NSN 4140-01-249-2513
NSN 6105-00-922-5114
NSN 6130-00-266-7496
NSN 5998-00-008-5786
NSN 5895-00-280-7528
NSN 4140-01-266-7187
NSN 5965-00-554-4138
NSN 6610-01-186-8798