The M4-0.7 x 30W9 JIS B1188 Phil Pan 304SS Split Washer 302/304SS Flat Washer Sems A2 Stainless 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 304 stainless steel, which is resistant to corrosion and rust. The washer has a split design, which allows it to be easily installed and removed. It is also available in a variety of sizes to accommodate different applications.