I used one of these for my headunit install, Basically, it plugs into the toyota wiring harness in your car, and on the other end has all the wires to join your pioneer head unit to. Its great, cause if you want to pull your headunit out and put the stock one back in, you just unplug it and walla you're done. Saves you from butchering your toyota harness.. Oh and the cables also have function of that particular wire printed on the cable - i.e - FL+, FL-, 12V, ACC ect. TRY HERE AGAIN Hope it helps. Chris