This adapter is designed specifically to adapt a European 13-pin vehicle wiring system down to the standard "Flat 4" used on 75% of trailers in North America. We merge a 13-pin European trailer plug together with the popular "Hoppy" adapter made by Hopkins Manufacturing to give you long-term dependable solution. If you have an Audi allroad, it most likely comes with a 13-pin trailer wiring harness already installed and this is exactly what you're looking for.