CDCO 5/8" Bore x 2-1/2" Diameter Single V-Groove Die Cast Pulley is designed for use with 4L or 1/2" x 11/32" belts. It has a hollow head set screw that allows for easy adjustment of the belt tension. This pulley is made of die cast metal, which makes it strong and durable. It is also available in a variety of sizes to meet your specific needs.