For controlling day length, the double layered SI-CA/CB screen brings 99.9% blackout – enough for the most sensitive plants. Choosing an aluminum upper side retains most heat. And for the under side, choosing black will avoid the unnecessary lighting. The unique knitted structure reduces condensation and allows them to be bundled to a small size for maximum available light. Its good permeable to water feature minimizes dew on the crop and risk of fungal diseases.