Polyken 557-MDT - 2" x 60yd UL Listed Metallized Duct Tape Acts as a superior closure system for use with flexible air ducts and air connectors. Recommended for use on UL list flexible air ducts in accordance with manufacturers' installation instructions. For use in heating, air conditioning, ventilating and refrigeration applications. Suitable for bonding, protecting, holding, repairing, and patching. Premium performance duct tape specially engineered for flex duct systems (PRINTED).