A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6650-00-196-5311
NSN 6645-01-569-0491
NSN 5996-01-248-0614
NSN 6105-00-630-4634
NSN 5990-01-364-8405
NSN 5925-00-825-3241
NSN 5925-01-331-6300
NSN 5998-00-421-7366
NSN 6685-00-700-1668
NSN 5905-00-556-5122
NSN 5935-00-882-1961
NSN 6220-00-736-2617