A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-01-026-1776
NSN 6150-01-511-1762
NSN 5985-00-952-6626
NSN 6145-00-061-6866
NSN 5925-01-438-7647
NSN 5915-00-314-0832
NSN 6620-01-474-4951
NSN 5945-01-445-6081
NSN 6150-01-468-0296
NSN 6105-01-407-8697
NSN 5835-00-978-1841
NSN 5905-01-525-5138