A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-00-010-8186
NSN 5915-00-605-7560
NSN 5920-01-512-8586
NSN 5960-00-993-8128
NSN 5930-01-400-6126
NSN 6220-00-263-4893
NSN 5996-01-466-4577
NSN 5950-00-005-9748
NSN 6620-00-124-4296
NSN 2925-00-578-4068
NSN 5910-01-367-2738
NSN 5985-01-428-9394