Improve the lighting efficiency of your indoor garden with durable Sunleaves Black and White Poly. The white surface reflects 90% of the light back to the plant canopy while the black surface prevents any light from penetrating through. The heavy-duty waterproof film also helps prevent algae and mold growth on walls. Users can double it up with the black surfaces together to economically and effectively partition off indoor gardens. Sunleaves Black and White Poly has a six-mil thickness.