A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5975-01-136-4359
NSN 5935-01-085-9943
NSN 6135-01-424-8130
NSN 6130-00-051-0810
NSN 5895-00-630-1868
NSN 6240-01-631-4066
NSN 6620-00-965-8075
NSN 6105-01-341-6142
NSN 6620-00-243-7766
NSN 6610-01-516-7278
NSN 6135-01-592-4139
NSN 6130-00-801-5359