Having USB power ports all over my truck is important, because so much charges off them nowadays. I can plug my bluetooth speaker or phone in here, when sitting out back of my truck. I also have a set of USB ports on the shelf in the truck cap, and ones up front. New with the wiring update is the ports are all switched -- so I can turn them off when I am not using them to keep the battery from being wore down over time. The yellow and green wires, which are dimmer-controlled power, run back to the overhead LED light strip.