8 Inch Backdraft Damper Back Draft Vent Duct Shutter Blocker, Backflow Ducting Insert One-Way Airflow Preventer with Inline Springs Loaded Folding Blades, HVAC Extractor Range Fan Hood Deflector

Very sturdy and higher quality than most

Seals well but the stove fan can’t even push it open against gravity unless it’s on high. Low (which still spins fast and loud) on my fan doesn’t even push it open upward so it just circulates hot air back down. Flap should be looser

I purchased 2 of these. Very pleased with them.

Just what I needed to retrofit into my Stove vent hood duct

Arrived within a few days. Good quality. I used it to prevent backdraft in a dryer vent. The air from the adjacent bathroom fan no longer goes into the dryer.

I really like the seal inside that the dampers seat against when closed. Fits perfectly in the 4" exhaust duct. Using it to seal out outside air from entering the indoor greenhouse through the exhaust fan duct.

With basic knowledge, I was able to install in less than 10 minutes. It prevents the backdraft that was present before the installation!

I opened up my recent installation and this does not work and constantly opens up with every small breeze from the exterior. What is the point if it lets air into the house and so slow to close because of weak springs. Total waste of time and money.

Have multiple dryer units operating and exhausting through a common vent. Check valves function satisfactorily.

I installed it as make up air intake. In theory should demand become nessary, it should open by demand and close when nessary.

sa vas très bien

The vent spring requires significant air flow to open. A fryer is fine but my range hood could not. The foam seal on the inside of unit provides an excellent backdoor preventer.