A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-00-220-2157
NSN 4140-00-057-5597
NSN 6685-01-449-1451
NSN 6620-00-658-6588
NSN 5975-01-273-3816
NSN 5895-01-032-5929
NSN 5975-01-364-2177
NSN 5910-01-322-8032
NSN 6240-01-262-2039
NSN 5910-01-381-3009
NSN 5996-01-045-7004
NSN 6110-00-862-3097