Acting as a thin mirror, Flora Hydroponics Mylar reflects nearly 98 percent of available light back to plants where it belongs. This metallic film can be taped or tacked directly to a flat surface or wall. Thicker two-mil Mylar is suited for most other applications like creating room divisions. Each roll is four feet wide. This is a 25' roll. Why pay more for cheap 1mil mylar when we offer 2mil at the same price. If another listing does not contain the thickness of their product, it is surely 1 mil Mylar. Flora only offers 2 mil Mylar. It is more durable and last longer.