Shurtape flex duct tape. HVAC UL 181B-FX Listed. For use on Class 1 Flex Duct. Used to connect, join, seal and patch flexible air duct. Tested in accordance with UL723; UL 181B-FX; UL Listed; US Green Building Council - LEED Point contributor product. Tape should be stored in its original packaging in a cool, dry area away from direct sunlight and should be used within 12 months of date of shipment. Surfaces to which tape is applied should be clean, dry and free of grease, oil or other contaminants. Adhesion to stainless steel: 42 oz/in width.