The Air Actuated electric trailer brake controller provides smooth brake actuation. The electric brakes on the trailer operate off the air brake system of the tow vehicle. When the brake pedal is depressed, the application of the electric trailer brakes is proportional to the vehicle's brake pedal pressure.Accommodated Number Of Trailer Axles: 1 To 3 AxlesType: ProportionalBrake Systems Type: 2 To 6 Brake SystemReverse Function: Fully Functional In ReverseDisplay: LEDWith Alarm: NoWith Wiring Harness: NoFeaturesOperates 2, 4, Or 6 Electric Trailer Brakes. Can Provide 18-Amp OutputAutomatic Or Manual Operation Of The Trailer Electric BrakesRed Indicator Light Shows Braking System Intensity And Proper FunctionCan Be Converted From A Negative To A Positive Ground SystemCompact Case Design With Black Textured SurfaceMounting Bracket And Screws Included For Easy InstallationLimited 1 Year Warranty