A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5925-01-143-5055
NSN 6610-00-186-9180
NSN 5950-00-315-3071
NSN 5996-01-087-0414
NSN 5990-01-256-8441
NSN 5985-01-069-8984
NSN 6240-00-965-7997
NSN 5965-01-191-0735
NSN 7035-00-981-7216
NSN 7035-00-631-3782
NSN 5835-00-351-9459
NSN 5930-01-256-8862