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.