A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5905-01-400-0532
NSN 5945-01-227-8309
NSN 5990-01-322-9781
NSN 5975-00-950-0588
NSN 5895-01-508-4524
NSN 5965-01-142-1807
NSN 6320-01-201-2776
NSN 5965-00-116-8982
NSN 5975-01-281-7270
NSN 6645-00-177-4729
NSN 6240-01-069-2688
NSN 6150-01-284-8471