A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6645-00-088-4079
NSN 5945-01-108-4672
NSN 5999-01-063-7408
NSN 6645-00-434-8793
NSN 5960-01-126-6245
NSN 5985-00-151-4538
NSN 5950-00-214-1625
NSN 7035-00-679-9027
NSN 6150-00-518-4558
NSN 5915-01-538-7581
NSN 5999-01-651-7914
NSN 4140-01-383-1862