A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-01-494-9858
NSN 5975-01-080-7455
NSN 5998-00-204-1729
NSN 5960-00-892-0990
NSN 5920-00-463-5057
NSN 6650-00-170-5095
NSN 6135-01-032-8887
NSN 5925-01-612-5131
NSN 6645-01-466-0185
NSN 6685-01-599-9831
NSN 5835-00-894-7374
NSN 5945-01-233-5810