This dual intensity controller allows you to adjust the intensity of the high beams using the vehicle's original switch. Simply connect this controller to the end of the wiring included with our light kits to enable the dual intensity feature. Mounting note: Vehicles equipped with LED headlights may use a ground-switched circuit, which will not activate the DataDim function with factory high beam controls. Vehicles with ground-switched headlights require the DENALI 2.0 DrySeal™ Hi-Low-Off waterproof switch in addition to the DataDim™ to toggle between high and low beams.