Light Rail Drive Wheel Replacement Kit, Robotic Grow Light Mover Genuine Fits LightRail 3.5, LightRail 4.0, LightRail 4.20 Much better yields when our grow lights move because more Leaf area is reached with better light, so no hot spots and no shadow patterns. Plus we cover about 30 percent more area, and that is per grow light. See ppfd chart below sponsored products Easy to install, the Drive Wheel Kit comes with one black per Motor. Compatible LR3.0, LR3.5, LR4.0, LR4.20. Only LightRail performs over many years with the power and endurance for any light at any weight Genuine LightRail, the one that meets important guidelines (see below) and solidly made in the USA since 1986. If it does not have the LightRail logo, see Motor photo, it is not a LightRail. Keep it Real, Keep it LightRail