Double bubble foil both sides, reflective foil insulation, 5/16″ thick with two outer layers of aluminum foil, each foil layer is bonded to a touch layer of polyethylene for strength, reflects up to 97% of the radiant heat with an r-value of up to 14.3 depending on application, excellent vapor barrier for below grade installation, class a/class 1 fire rating, approved by boca, icbo, sbcci, ccmc, ftc-compliant, is non-toxic, non-carcinogenic, lightweight & can be installed with scissors, staples & tape, hundreds of applications: wall, roof & basement, garage door, camper, metal or pole barn, window coverings, stables, hatcheries, etc, sell by linear foot or roll.