Avoid damage to your towed vehicle! Make certain that your supplemental braking system is properly placed and operating effectively. This kit activates your RV monitoring system to alert you when the brakes of your towed car are being applied. This switch sends a beam of infrared light to detect brake pedal movement. When the pedal moves down, it sends a signal to the monitor that the brakes have been applied. LED pulse confirms system activation Just three wires - connect to the power, ground & the brake light wire | Roadmaster Universal Stop Light Switch Kit