The M4 x 10W8 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 over a larger surface area. It is made of a zinc-plated steel and has a split washer design that helps to prevent the screw or bolt from loosening. The washer is 10mm in diameter and has a thickness of 0.8mm. It is suitable for use with M4 screws or bolts.