Nilight Nilight Dual Output Vehicle Side 7 Way RV Blade and 4 Way Flat Wiring Harness Multi Tow 4Pin to 7Pin Electric Adapter for RV Truck Factory Tow Package USCAR 7 Way Sockets Required, 2 Years Warranty. This wiring sockets has a 7 way RV USCAR plug which is ready to connect to vehicle with the 7 way USCAR socket.