24 inch x 10 feet, square edge roll double bubble foil both sides, reflective insulation, 5/16 inch thick with two outer layers of aluminum foil, each foil layer is bonded to a tough layer of polyethylene for strength, reflects up to 97 percent of radiant heat with an R-value up to 14.3 depending on application, excellent vapor barrier for below grade, can be used for radiant floors, crawl spaces, duct insulation, metal buildings, basement walls and attics, product has been evaluated by the following: icebox, comic, Boca, sickie and Dade county, easy applied with tape and staples.