When Mylar is used in the indoor garden, this means that no precious light is wasted — it stays on the plant where it belongs! Almost 98% of the light striking Mylar will be reflected; making it the ultimate indoor garden surface. A metallic film, almost like a thin mirror, Reflective Mylar is taped or tacked directly to a wall or other flat surface. The 2mm thick Mylar is strong. It can be used when durability is important, such as mounting to wood or hanging from the ceiling as a room divider. All rolls are 4′ wide and come in a variety of lengths.