UR-Standard Pulley with Lag Screw Ideal size pulley for use with your VSB Automatic Chicken Door Opener Uses 3/8" wrench for lag screw, threaded for 1" into wood. Smooth rolling High quality hardware for indoor/outdoor use Accessory for sliding gates on poultry houses, permitting the operation of several gates by one VSB Unit Sold as 1--Pulley and 1--3/8" x 1.5" Wood Screw