The combiner box is buried in there under the rail. You can see the cables turning outward there. The box is mounted on the reefer chimney and has a hole in the back so that all connections are weather proof and cable goes directly into chimney. I stuffed about eight feet of 1-1/4" PVC down the chimney to protect the cables from the heat of the reefer coils. I also have the cables for my DirecWay Satellite Internet dish and my Wilson Cell Phone antenna going down that makeshift raceway.