The CF Backdraft Damper attaches to inline ventilation systems to keep
exhausted air out for good. When used in conjunction with a Can Fan and
carbon Filter, the CF Backdraft Damper also helps control odors as it
prevents any untreated air from escaping the enclosed area. The
directional damper installs downstream from the fan: when the fan turns
on, the airflow opens the damper, and when the airflow stops, the
damper closes. This eight-inch CF Backdraft Damper fits any standard
eight-inch ventilation ducting.