Reese Towpower 78119 Adapter with Built-in 12V Power Outlet (7-Way Blade to 4 or 5-Way Flat) Easily adapt OEM 7-way blade connector to basic 4-way or 5-way flat connector Built in 12 volt power outlet Instantly checks basic trailer electrical circuit for connectivity Displays connectivity using high visibility LED's Attached dust cover keeps terminals clean when not towing and an extra attached terminal plug to cover 5th post of 5-flat when only using the 4-flat connector