This trailer adapter is used to adapt from a 7RV trailer connector on your tow rig to a 6 pin connector on your trailer. The 7RV is what is on most newer trucks and SUV's. The 6 round pin is an older connector that is not uses as often any more. The 7RV has 6 spade connectors around 1 center pin. This adapter will run your brake lights, running lights, right turn signal, left turn signal, electric brakes, and the charger for your break away battery. This adapter does not use the center pin on the 7RV connector (it is normally just axillary).