This is a replacement Breakaway Switch by Tekonsha for your Electric Trailer Brakes, or Electric over Hydraulic Trailer Braking System. Rated for use with 1 to 4 Braking Axles, this switch can be easily installed with a single bolt (not included) or welded to the trailer's frame. Breakaway Switches are required by law in some locations, but are always a smart option to add to your trailer. Should the trailer become disconnected from the tow vehicle, a breakaway switch like this one will activate the trailer's brake and cause it to come to a stop.