A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6610-01-157-0426
NSN 6620-01-129-4790
NSN 5935-01-556-6883
NSN 2925-01-209-3584
NSN 5915-00-258-0031
NSN 5996-00-264-0710
NSN 5855-00-586-6255
NSN 6620-01-517-0014
NSN 5950-01-371-2009
NSN 5985-01-125-6788
NSN 5998-00-891-8799
NSN 6220-00-578-6539