The breakaway systems will automatically apply consistent braking power to your trailer brakes if a breakaway occurs between your vehicle and trailer. For use on 1, 2, 3, or 4 axle trailers equipped with electric brakes Meet or exceeds DOT specifications regarding trailer breakaway and holding requirements Weather/corrosions resistant, heavy duty polymer case to protect the battery and charger Includes Polymer battery case with A frame or post mounting bracket (part #852018), rechargeable sealed 12V 4 AMP-hr lead acid battery and terminals (part #852023), and breakaway switch (part #852010)