AC Infinity Backdraft Damper Ducting Insert 8-Inch Black GalvanizedDescription An antidraft duct insert designed for use with range hoods, bathroom fans and other home HVAC applications. Features outer rubber gaskets that create an airtight seal and grip between the damper and ducts. Mounts horizontally or vertically to prevent backflow and debris from entering ducting. Galvanized steel body with spring loaded aluminum damper blades that open with minimal airflow. Fit for 8 in. Duct Openings Product Length: 5. 03