From the Manufacturer Reflectix is a 5/16-Inch thick, seven layer, reflective insulation which is available in rolls of various widths and lengths. It is used extensively in both specialty and standard construction projects. Two outer layers of aluminum foil reflect 97-Percent of radiant heat. Each layer of foil is bonded to a tough layer of polyethylene for strength. Two inner layers of insulating bubbles resist conductive heat flow, while a center layer of polyethylene gives Reflectix high reliability and strength. Reflective insulation for use in a crawl space, attic, wall, metal buildings and post and frame structures Fiber free, environmentally safe, easy to install and lightweight Made up of seven layers, two outer layers of aluminum foil reflect most of the heat which hits them Each layer of foil is bonded to a tough layer of polyethylene for strength Two inner layers of bubble pack resist heat flow, while a center layer of polyethylene gives additional strength