The Ultra Clear Vented Humidity Domes from Super Sprouter® feature built-in light tracks that accommodate the 18-inch Super Sprouter T5 HO Grow Light Fixture. The light tracks are directional to allow the light to run the length or width of the domes, enabling two trays to run side by side. Vertical sides allow the use of all plant sites in a propagation tray. Two vents in the top of the dome can be opened or closed to control humidity. These clear, transparent domes allow for maximum light penetration and the best viewing of your plant starts.