Get instant feedback on towed car brakingÃwirelessly! High-power 900 MHz radio transmitter connects to towed vehicles brake light switch. Receiver plugs into dash 12-volt accessory outlet and gives you audible and visual alerts when towed car braking is taking place. Designed for use with Air Force One and Stay-IN-Play DUO auxiliary braking systems. Also works with other brands of auxiliary towed car braking systems. | Demco Wireless CoachLink