A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5999-01-099-9782
NSN 5925-00-324-2996
NSN 5990-01-627-8097
NSN 6110-00-896-3618
NSN 5930-01-400-6126
NSN 5996-00-597-2234
NSN 6240-00-507-8987
NSN 5920-00-876-3312
NSN 6620-01-207-0667
NSN 5975-01-050-8114
NSN 6685-00-689-6510
NSN 5998-00-196-1407