Easily determines the charge capacity of your trailer's battery. This hybrid unit has a pus-to-test function with LED indicator that let's you know if your battery is fully charged or needs recharging. Unit is also a breakaway kit that applies trailer brakes in the event that the trailer becomes disconnected from your hitch while in motion. Kit includes a 5 amps/hour battery, a breakaway switch with 7-1/2" lead wire and battery box. Use on trailers with up to 3-axles.