The Perfect Stop gadget will help to park your car in the garage perfectly in the center. The principle of operation is simple - the box is attached to the ceiling of the garage and lowers the ball on the cable when the gate is opened. You need to drive up so that you touch the center of the windshield. The system is compatible with any garage door operator - you simply mount the unit to the ceiling using the fasteners provided. Installation takes minutes. As for the ball, it is made of foam material, which will not scratch or damage the car glass.