A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-00-116-6590
NSN 6240-01-441-0784
NSN 6110-00-187-4537
NSN 6620-01-163-3329
NSN 6650-01-437-8852
NSN 5930-00-863-1021
NSN 5960-01-412-9474
NSN 6150-00-840-9346
NSN 5905-01-216-4519
NSN 6610-01-307-0911
NSN 5930-00-835-9292
NSN 2925-01-522-5631