Safely and effectively apply the load from your trailer lighting to the battery and not to the rest of the bike's electrical system. Eliminate blown fuses caused by overloading stock lighting or accessory circuits. The relay harness utilizes inputs from the motorcycle to direct power from the battery to the appropriate trailer lighting circuit.; Plug-and-play kit that plugs inline underneath your seat to the bikes main rear harness Kits finish up by connecting directly to your battery and wiring to your trailer plug Add 5 to 4 Converter for trailers with 4-wire connectors Plugs right inline to the Kuryakyn Trailer Wiring Harness and Relay