A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5999-00-155-8066
NSN 5975-01-133-2738
NSN 5915-01-290-3885
NSN 6135-01-421-1052
NSN 5996-01-125-5781
NSN 5935-00-081-4181
NSN 5985-01-651-0688
NSN 5925-01-461-3594
NSN 6220-01-171-0957
NSN 6105-00-519-2092
NSN 5985-01-393-5786
NSN 6610-01-209-5387