The Can Fan Backdraft Damper attaches to inline ventilation systems to prevent exhausted air from returning. 

If you vent outside, a backdraft damper helps prevent outdoor air from seeping into the ventilated area when the exhaust fan shuts off, giving you better temperature control of the growing area.

When used with an exhaust fan and carbon filter the CF Backdraft Damper will further improve odor control in your growroom as no untreated air can escape.

Be sure to install this directional backdraft damper downstream of your fan. When the fan activates, the airflow automatically opens the damper. Once the fan turns off, the damper closes.

Sizing is simple - measure the diameter of your ducting and match it to the Can Fan Backdraft Damper size. Fits any standard ventilation duct.