The M4 x 8W9 JIS B1188 Phil Pan Split Washer Flat Washer Sems M/S Zinc Yellow is a type of washer that is used to distribute the load of a screw or bolt. It is made of metal and has a split washer on one side and a flat washer on the other. The split washer helps to prevent the screw or bolt from loosening, while the flat washer helps to distribute the load of the screw or bolt. This type of washer is often used in automotive and industrial applications.