The RK1260 Relay Kit features a premium quality, fully sealed relay that's been tested by REDARC engineers to stand up against the harshest of environments. It allows a BCDC to be installed in a trailer that is being towed by a vehicle that is equipped with a smart alternator, thereby triggering the ignition source inside the vehicle allowing it to start and stop charging. The Relay Kit is equipped with everything you need. It includes heat sink, relay holder, butt-splice connectors, 60A/80A sealed changeover relay with 3/8"contact pins, and a detailed installation instruction sheet.