Chicago Die Casting 5/8" Bore x 2" Diameter Single V-Groove Die Cast Pulley is for use with 4L or 1/2" x 11/32" belts. It has a hollow head set screw for easy installation and adjustment. For A belts, pulleys from 2 inch to 12 inch have keyways except 3/8 inch and 1/2 inch bores and 3/4 inch bores in pulleys less than 4 inch in diameter. All pulleys are with slotted headless set screws.