CURT Dual-Output 4-Way Flat Vehicle-Side to 6-Way Round Trailer Wiring Adapter Model 57604CURT Dual Output 4 Way Flat Vehicle Side to 6 Way Round Trailer Wiring Adapter Model 57604 There are several different types of connectors used to supply power from a tow vehicle's electrical system to a trailer's wiring system. Some trailers only need the bare essentials running lights, brake lights and turn signals while others require a connection for reverse lights, electric brakes and auxiliary power. With connectors ranging from simple to