Nilight 7 Pin Male Trailer Round RV Blade Connector Socket 7 Pole Trailer Plug Heavy Duty 7 Way Vehicle Side Replacement Plug Socket 6-24V for Trailer Tow Hitch Car RV Boat Truck, 2 Years Warranty. This 7 Pin Round RV Blade Adapter can be spliced into your existing vehicle wiring for towing trailer with 7-way RV-style. To connect the taillights, brake lights, reverse lights, turn signals, trailer brakes and auxiliary power.