A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-00-805-2557
NSN 5895-01-106-2912
NSN 5990-00-455-9865
NSN 6135-01-442-7275
NSN 5920-01-546-3222
NSN 6620-01-508-1996
NSN 6610-00-935-5190
NSN 5975-01-110-7396
NSN 6135-00-122-2420
NSN 5835-00-152-5516
NSN 5905-00-406-4312
NSN 6150-01-322-8112