A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6135-01-327-2092
NSN 6110-00-244-0427
NSN 6105-01-587-8522
NSN 6620-01-265-2887
NSN 6135-00-738-5571
NSN 5985-01-474-5141
NSN 5990-01-426-7350
NSN 5945-00-366-5301
NSN 5910-01-603-8689
NSN 6650-01-181-6037
NSN 6685-01-145-3938
NSN 6145-00-358-6700