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

Good price fast shipping excellent seller

as described

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.

Stops outdoor odors and easy to install!

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.

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

I purchased 2 of these. Very pleased with them.

This is a good quality, well built dampener. It uses a high density foam weatherstrip on the back for the wings to rest against. This helps seal it up nicely when not in use. This is FAR better than the typical Chinese junk you see. Very happy and will recommend to all.