Syncronizer trailer brake control, manufactured by Hayes Hemmerz, is the safest time based brake box available. Vehicle and trailer stoplights are operated for additional safety. It is for use on tandem or single axel trailers with 2 or 4 electric brakes. Manual or automatic operation provides great convenience. With multiple holes and brackets and the "Quick-Connect" feature, installation is simple. An automatic current limiter helps prevent short outs. No leveling is required, as this brake box is self-adjusting. 3 year warranty included.