A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5998-01-010-3576
NSN 6645-00-350-6029
NSN 5990-01-460-6390
NSN 5910-01-328-7909
NSN 6105-01-290-4738
NSN 6620-01-367-0844
NSN 5996-01-641-7258
NSN 5905-01-463-9131
NSN 5925-00-475-2648
NSN 6220-01-065-2171
NSN 6220-01-437-0385
NSN 6685-01-508-0494