An electronic brake controller is a must-have for running trailer brakes. The controller powers the electric brakes and controls how much force is applied by way of electrical current. This particular unit from Prodigy is a progressive controller that adjusts for speed and brake sensitivity. A progressive controller takes the guesswork out of dialing in your electronic brakes and, once you have the initial settings dialed in, works trouble-free. A brake controller is not only a great way to save your tow rigs brakes, but if the trailer gets loose or out of control it is a great failsafe to get the trailer back in check.