Polyken 339 COLD WEATHER PREMIUM FOIL TAPE - UL181A-P & B-FX Listed New & Improved Formulation - Cold weather printed aluminum foil backing for fiberglass duct systems and flexible duct closures. Applications Recommended for use on UL listed fiberglass duct board in accordance with manufacturers' installation instructions. Meets UL 181 A-P standard for use as a closure material on fiberglass duct systems and UL-181 B-FX standard for use on flexible air ducts and closures. Features & Benefits High performance acrylic adhesive. Excellent vapor barrier properties. Resists mold & mildew growth. Conforms to ductboard. Improved tack and shear properties. Tear-resistant. Instant adhesion/superior quick stick. Maintains permanent seal over wide temperature range. (Max. temp. 325ºF). Suitable for installation temperatures as low as -10ºF.