Shop 7 Way to 5 Way Trailer Plug Adapter 7 Pin Round to 5 Pin Flat Blade Add Reverse Lights RV Blade to Trailer Flat Heavy Duty Connector for Tow Hitch Car RV Boat Truck in high quality, support 2 Years Warranty. 5-pin trailer wiring is similar to 4-pin wiring, but it adds a blue wire for the reverse or backup lights. This Trailer Adapter designed to connect and transmit electrical signals between the tractor and the towed vehicle.