A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5985-01-237-7721
NSN 6220-00-230-0807
NSN 6610-01-168-7943
NSN 6150-01-439-1378
NSN 5930-00-788-1408
NSN 5999-01-004-8270
NSN 6610-01-272-9691
NSN 5855-00-760-3870
NSN 4140-01-484-0649
NSN 6150-01-458-5932
NSN 2925-00-770-4713
NSN 5960-00-774-8227