This right-hand wound residential spring failure device is designed to help prevent uncontrolled garage door movement if a torsion spring breaks. It is compatible with 2” spring fittings and tube shafts and uses a 3-3/8” shaft offset. One device is required per spring. The locking wheel includes two set screws and one self-drilling screw for installation. Maximum supported door weight is 150 lbs. with one spring and up to 470 lbs. with two springs. Sold individually.