A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-01-480-0507
NSN 5998-01-212-3123
NSN 6610-01-192-6478
NSN 6685-01-331-7090
NSN 7035-01-141-3041
NSN 5925-01-110-8835
NSN 5935-01-519-8454
NSN 5935-01-060-1174
NSN 5905-01-449-8238
NSN 5915-00-501-4420
NSN 6650-01-625-4668
NSN 6620-00-280-2874