As the number one brand in towing electrical products, Hopkins Towing Solutions has provided consumers with innovation, durability, and performance for over twenty years. Hopkins' pre-wired adapters allow the consumer to create a custom Plug-In Simple wiring system appropriate for any towing situation. Take advantage of your existing 4 Flat when adapting. The 4 Wire Flat Adapter attaches to an existing 4 flat to bring the lighting functions to the 6 pole round connector, leaving electric brakes, auxiliary power, and ground as the only functions that need to be wired.