A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6135-01-140-8201
NSN 6150-01-442-1592
NSN 5975-01-652-3792
NSN 6645-01-633-1852
NSN 5985-01-603-2183
NSN 5999-00-035-9288
NSN 6620-01-611-7907
NSN 6320-01-160-8578
NSN 6220-01-573-1094
NSN 6135-00-900-2139
NSN 6650-00-473-1259
NSN 6685-00-981-5114