A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6610-01-183-4470
NSN 6145-00-882-6723
NSN 6645-00-145-6411
NSN 6240-01-177-3305
NSN 6610-00-027-1284
NSN 5999-01-589-4977
NSN 5999-01-565-8801
NSN 6320-01-160-8578
NSN 5935-01-222-0856
NSN 5965-00-577-6215
NSN 5975-00-929-4602
NSN 5960-01-573-6483