Smart : is the safest and most responsive system you can install. The proportional trailer brake controller automatically detects when the towing vehicle slows down or stops. This type of brake controller replicate your own strength for the trailer's brakes, whether you are stopping slowly or have to on the brakes Easy to Display: The LED digital display shows the voltage delivery from the brake controller to the trailer brakes. Easy to read, easy to observe the vehicle's condition in real time. In case of emergency, timely adjustment and more stable: Suitable for 1 to 4 axle trailers, transmits the signal of the vehicle's brakes to the trailer, and can adjust the power (result) and program rate (synchronization) to adapt to your inclination, street conditions and trailer type, improving driving safety. No leveling required Quick installation and use: The wiring port can be used for vehicle-specific brake controller harnesses and provides a quick connection between the controller and the towing vehicle for quick and easy installation or removal 4 wiring and control: black vehicle power, red brake light, white vehicle ground, blue trailer brake Note: If there is an error code before use, you can try to loosen the 5 screws on the back of the product until the code disappears. Some products may be installed due to the screws being too tight and compressed Colour:Black Material:Plastic + Metal Package Contents: 1 x Trailer Brake Controller Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.