A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5835-01-558-9444
NSN 5990-01-183-1897
NSN 5855-01-372-9728
NSN 5999-01-391-8201
NSN 7035-00-753-0695
NSN 5920-01-106-1137
NSN 5920-00-607-3385
NSN 6645-01-507-9179
NSN 6240-01-515-1553
NSN 6105-01-418-1877
NSN 6130-01-165-1127
NSN 5998-01-139-7382