A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5835-01-644-8013
NSN 6620-01-412-5514
NSN 5920-01-143-5002
NSN 5855-01-263-7669
NSN 6105-00-846-1793
NSN 5915-00-269-4463
NSN 7035-00-929-0363
NSN 6110-00-006-6381
NSN 6220-00-426-1963
NSN 6130-01-545-8322
NSN 6650-00-480-9135
NSN 5895-01-465-0264