A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-01-445-6004
NSN 7035-01-319-2315
NSN 6145-01-038-9725
NSN 5990-00-161-2797
NSN 6145-00-903-1939
NSN 6620-00-709-7389
NSN 5945-00-909-1216
NSN 5996-01-561-8910
NSN 5915-01-040-6772
NSN 5895-01-512-0488
NSN 6110-00-271-9928
NSN 6240-01-582-5803