A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6220-01-296-9571
NSN 5965-01-476-8539
NSN 6130-01-252-8823
NSN 5975-00-682-7759
NSN 5990-00-325-8513
NSN 5905-01-631-9144
NSN 6220-00-932-4992
NSN 5895-01-478-4588
NSN 5930-01-220-1016
NSN 5930-01-013-7895
NSN 7035-00-585-2113
NSN 6150-00-120-2485