Lights Module 8 High Mod:This 8 high mod allows your high beams,low beams, fog lamps and day time running light to be on simultaneously when turn on high beams. Greatly improve illumination on dark country road at night.Notification: low-beams fog lights and DRL will function normally,when the high-beams are not turned on. Compatibility:The module light compatible with 2003 2004 2005 2006 2007 chevy silverado and gmc sierra 1500/2500/3500,2003–2007 GMT 800 trucks,2004-2006 yukon, 2004-2006 tahoe,2003-2006 avalanche 1500,2004-2006 escalade,2003-2006 escalade ext. High Performance:Made of FR-4 PCB Materials,solid construction,durable and much safer to use. Easy Installation:Find your fuse box,pull out 4 relays labeled Fog Lp, Hdlp-Low,Hdlp-Hi,Drl. Lay down the circuit board and reinstall those relays back into original location.No modification to existing wiring.It took less than 5 minutes to install. Package Including:1 pcs module light. Compatible with GMC：for 2003-2007 Sierra 1500/2500 HD, 2003-2006 Sierra 3500, 2003-2004 Sierra 2500, 2005-2006 Sierra 1500 HD, 2004-2006 Yukon , 2007 1500 Classic/1500 HD Classic/2500 HD Classic/3500 Classic/3500 HD, 2003 Sierra 1500 HD

Compatible with Chevrolet:for 2003-2006 Avalanche 1500/2500, 2003 Silverado 1500 HD, 2007 Silverado 1500 Classic/ HD Classic, 2007 Silverado 2500 HD Classic, 2007 Silverado 3500 Classic/3500 HD

Compatible with:for 2004-2006 Escalade, 2003-2006 Escalade EXT

Compatible with GMT800:for 2003–2007 GMT 800 trucks