1. This electrical adapter is designed for connecting European 7-way style connector on vehicle to US standard 4-way flat on trailer 2. Fast, easy plug-in installation, minimize the hassle of installing any new wiring inside, no other adapters needed 3. Included a dust cover on the American style 4-pin plug side to keep your connector clean when not in use 4. This single-function adapter transfers the power to trailer with L/R turn signals and taillights 5. Wiring Euro 7-pin vehicle-end connector to trailer with US 4-pin flat trailer wiring