MIVIDE 2Pack 4 inch Backdraft Damper Duct, One Way Airflow Ducting Insert for Ducting in Range Hoods, Bathrooms Fans and kitchen Fan

PRODUCT SIZE: Diameter 100MM/4 inch, length 88MM/3.5 inch, thickness 0.5MM/0.02 inch. Please confirm the size before purchase. HIGH QUALITY MATERIALS: Galvanized steel damper is made of quality galvanized steel, and the axis and spring are made of stainless steel, product Very solid and well made, good tension on the spring. EASY TO INSTALLATION: The backflow flap is installed by inserting it into the ventilation pipe until it stops. The position of the spring should be horizontal for horizontal installations so that it can open and close optimally. The backdraft shutter is installed so that the damper blades open only in the outflowing air direction. PRACTICAL DESIGN: Backdraft damper has a smooth-running spring. The backflow flap opens and closes automatically at low air volumes. Backdraft damper can ventilate an area to avoid toxic fumes from building up. WIDE RANGE OF USAGES: These draft blocker set can be widely applied in exhaust fan pipe, a dryer duct, range hoods, heating ducts, vents and other residential and industrial applications