For controlling day length, the double layered GLH 00 FR W/B+B brings 99.9% blackout – enough for the most sensitive plants. Choosing an aluminum upper side retains most heat, while white is better for cooling. And for the underside, choosing white will intensify the effects of supplemental lighting. Their unique knitted structure reduces condensation and allows them to be bundled to a small size for maximum available light. They are UV stable and remain clean and effective for a long time. This product is made from flame retardant materials alone, this is the optimum choice for all installations from a fire safety perspective. It meets the highest safety standard in the horticultural industry and test reports are available from various authorities.