Since RV'ers got away from 12 volt TV's and generally use regular TV's and inverters some manufactures stopped putting 12 volt plugs into trailers. My toy hauler didn't come with any. Its an easy install where you can usually hook into an existing 12 volt light or switch wiring. I put one in the main living area using the wiring running to some under cabinet lights and another in the bedroom where I pulled power from the light switch. In both cases the trailer wiring is 10ga so its big enough to powder a 12 volt plug and a couple led lights. Depending on what you want to charge you might want to install a single or double USB plug instead of the standard 12 volt socket. I put a 12 volt socket in the living area but all it ever has plugged in is a USB adapter so when I did the bedroom I just put a double USB plug in. Have a couple of each might be a good idea.