LightRail 710065 entension Rail, 3', Brown/A LightRail moves your lights over the tops of the plants, reducing shadow Patterns and getting the correct Intensity of light on the leaves for optimum leaf area index  the single most important factor in increasing your yield Youll get much better yields plus up to 20% more area covered  you save energy and money, and with much better results LightRail is the single best way to get more from your grow lights