A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5930-01-242-9918
NSN 6240-01-097-3934
NSN 5935-01-089-5760
NSN 5950-01-543-9640
NSN 6620-01-254-7963
NSN 6150-00-935-3317
NSN 6105-00-900-4143
NSN 5835-00-160-7142
NSN 5975-01-019-1553
NSN 4140-01-186-6453
NSN 6135-00-728-9860
NSN 5915-01-160-7123