A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5960-00-266-6741
NSN 5996-01-595-6529
NSN 5935-01-269-9551
NSN 6610-00-751-7916
NSN 6610-01-467-7068
NSN 5925-01-390-1332
NSN 5965-01-408-6218
NSN 5855-00-532-0025
NSN 5930-01-634-0659
NSN 5945-00-314-6866
NSN 5998-01-613-3771
NSN 6220-01-280-5353