Hon&Guan 4 Inch Backdraft Damper with 4 x 8FT Aluminum Foil Insulated Flexible Duct

Upgrade design The 4 inch damper on both sides of the top and bottom of the two new concave inward pressure rib, and increase the thickness to 0.6mm,to ensure that the product is more solid, not easy to damage., Wide applications Back draught valves can be inserted into ventilation ducts which are flexible or non-flexible. Designed for use with dryer vent backflow preventer, range hoods, bathroom fans, kitchen and other home HVAC applications., Material The backdraft damper and the flap leaves is made of a galvanized steel, the axis are made of aluminum, while the spring are made of carbon steel.,Low Noise Silencer: 4 inch duct designed for reducing noise from fans and carbon filter systems, can decrease the noise by up to 50%,3-Layer Tough: Hon&Guan dryer exhaust hose keep your ventilation system free of rips and pin holes. The dryer duct is built with 2 layers of aluminum foil with a layer of PET and steel wire helix to preserve the shape, keep your ventilation system free of rips and pin holes