Used mainly on older model doors and included in all restraint models. Used to keep the door from being lift off the track. For hollow doors, use small tabs included in kit and locate above and at ends of door edges. One on door top frame at door strike side frame and other opposite door strike frame, on door top frame, centered directly above door edge when door is fully closed. (Tabs are set height and cannot be adjusted like "Anti-Rotation Screw".)