go to www.trailerwiring.com, select "electronic taillight converters" under products, and look at item #48845, that is the one I got, its the brand most auto parts stores carry. The one I got looked slightly different (rectangle case) but preformed the same function, im guessing thats just a new version.

I HAD it setup so the outer circles of each light were the combination lights, and the inner circles were brake & tail lights. I took the lights off the car though, I have the chrome lights, which stand out too much for me on a dark car.