A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5999-00-186-3976
NSN 5920-01-076-7045
NSN 5910-01-398-0621
NSN 5925-01-625-4428
NSN 6620-00-189-0967
NSN 5945-00-941-6056
NSN 5910-00-097-8062
NSN 5935-00-861-2793
NSN 6610-00-774-2680
NSN 5960-01-133-3551
NSN 5950-00-908-4251
NSN 6620-00-613-3023