A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5855-00-943-0685
NSN 6620-01-045-4467
NSN 5835-01-158-6878
NSN 6145-00-110-9410
NSN 5996-01-577-8354
NSN 5915-01-421-1818
NSN 5920-01-501-0674
NSN 6645-01-182-4896
NSN 6610-01-399-5222
NSN 5835-01-520-4479
NSN 5855-01-519-4991
NSN 6135-01-125-4867