This used to power a Pi in an outdoors enclosure, it's about 8-10m of DC power line feeding a UBEC with a Micro USB connector, so you feed 12V from something like an LED power supply into one end and it outputs 5VDC from whatever's left of the 12V at the other. This deals with the fact that you can't feed 5VDC over any kind of distance and still expect to get 5V at the other end. Also has a 12V barrel connector for feeding 12VDC devices about halfway along it.