A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5999-00-565-8857
NSN 5835-00-572-7445
NSN 6620-01-122-8886
NSN 5855-01-105-7793
NSN 6650-01-553-2805
NSN 7035-01-258-7661
NSN 5910-00-914-0165
NSN 5835-01-632-6627
NSN 5965-01-026-8624
NSN 5925-00-985-8344
NSN 5855-00-198-3197
NSN 5990-01-177-2838