The M4 x 12W9 JIS B1188 Phil Pan Split Washer Flat Washer Sems M/S Zinc is a type of washer that is used to distribute the load of a screw or bolt over a larger surface area. It is made of zinc-plated steel and has a split washer design that helps to prevent the screw or bolt from loosening. The flat washer provides a smooth surface for the screw or bolt to bear against, and the split washer helps to dig into the surface to create a more secure hold. This type of washer is commonly used in automotive, construction, and other industrial applicat