These M4 x 20W8 JIS B1188 Phil Pan Split Washer Flat Washer Sems M/S Zinc Yellow are designed to be used with M4 screws and have a washer diameter of 8mm. They are made from steel and have a zinc yellow finish. These washers are split, which means they can be easily installed and removed without the need for tools. They are also flat, which means they will not interfere with the tightening of the screw. These washers are ideal for use in a variety of applications, including automotive, construction, and manufacturing.