UFP DX7.5L A60 Disc Brake Surge Actuator - Single Axle This UFP by Dexter disc brake surge actuator works by the surge or push of the trailer toward the tow vehicle. This automatically synchronizes the trailer brakes with the tow vehicle axle brakes. When the trailer pushes against the tow vehicle, the actuator telescopes together and applies the force to the master cylinder, supplying hydraulic pressure to the brakes. Product Features UPF Model 34043 Capacity 7,500 lbs 1 Axle Application Fits 2