A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-364-0444
NSN 6240-00-158-2808
NSN 5945-01-590-1148
NSN 5895-01-401-5388
NSN 5960-01-593-1936
NSN 5999-00-079-0368
NSN 5855-01-381-7493
NSN 6645-00-070-8277
NSN 6620-01-054-9346
NSN 6650-01-475-3714
NSN 5985-00-917-5034
NSN 6145-01-169-9657