A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6240-00-102-4003
NSN 6105-01-147-6550
NSN 5945-01-258-5042
NSN 6105-01-322-8944
NSN 6645-01-352-6583
NSN 6105-01-363-1288
NSN 5930-01-056-4091
NSN 7035-00-020-2227
NSN 5895-00-064-8065
NSN 5990-00-181-2220
NSN 5925-00-834-0272
NSN 6620-00-262-3113