A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6610-00-625-9478
NSN 6320-01-056-1164
NSN 6240-00-389-4822
NSN 5920-01-419-7737
NSN 5930-01-503-7162
NSN 5835-01-373-9506
NSN 5910-01-425-2313
NSN 4140-01-263-8404
NSN 5855-01-634-0259
NSN 6105-00-573-9044
NSN 5910-00-423-7765
NSN 5910-00-452-5957