24" x 10', square edge roll double bubble foil both sides, reflective insulation, 5/16" 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% 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 & attics, product has been evaluated by the following: icbo, ccmc, boca, sbcci & dade county, easy applied with tape & staples.