Certified according to ULC S110/UL 181, this insulated flexible air duct is composed of four (4) layers of polyester encapsulating a galvanized wire; all assembled with a flame retardant adhesive. Fully water repellent, the duct is corrosion resistant as well as high static pressure thanks to the unique four-layer lamination process and wall thickness. The insulation contains no hazardous substances that may pose a health hazard.