A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-462-1555
NSN 6105-00-142-5901
NSN 4140-01-280-5364
NSN 5996-01-139-2843
NSN 6150-01-255-9048
NSN 5930-00-774-5553
NSN 6645-01-552-4570
NSN 6240-01-492-6147
NSN 5915-01-108-4552
NSN 5950-00-500-2709
NSN 5975-01-528-5463
NSN 5835-00-065-6757