The LightRail 4.0 AdjustaDrive Motor has both a 0 to 60 second adjustable time delay for pausing the grow light at both ends of its travels, promoting even growth from end to end; but it also has a 2 to 4 feet (.6 to 1.2 meters) per minute adjustable speed control as the Motor goes along the Rail. This feature covers a wide range of grow light intensities and travel distances, and provides considerable flexibility. The LightRail 4.0 AdjustaDrive Motor is the ultimate in light mover control and is compatible with all LightRail 3.0, 3.5 and 4.20 Rails and accessory items. Note: This is the Motor Only together with Switch Stops mounting hardware, instructions and a two year warranty – no Rail is included. This is ideal if you already have a Rail or of you prefer to purchase a one piece, 2-meter (6’6” total length) Rail separately.