4 Inch Draft Blocker Backdraft Damper Duct Draft Stopper One-Way Airflow Ducting Insert Backflow Preventer Inline Fan Vent Deflector

Wasnt avail at big box stores near me so I scrambled to order this for my contractor installing the ductwork for my new kitchen stove vent. He said it was perfect and easy to install. It seems to be working great and our city inspector specifically went out of his way to check it. Passed without issue. Recommended.

Perfect for my installation. Too many of these type dampers have very stiff springs and it will not work with low CFM air flows. These are great. You can blow at them with your mouth and get them to open. And they seal very well. I use them for air circulation between rooms with fans set to about 60 CFM. The last ones I got restricted about 80% of the air. These only restrict maybe 10%. This is key for low CFM situations like bath exhaust fans, for instance.

pretty light weight but I think that's by design. Alum so no rust worries - very light spring action. Fit perfectly in the existing duct work. I wasn't able to use the baffle on the fan I bought for the bathroom so this was a nice alternative.

Pretty good. It stopped the bad backdraft I had, but the center hinge has a bit more gap than I'd like.

This draft blocker worked perfect. I was concerned it wouldn't fit inside my old pipe and yet have my old elbow Go over it. It works great to prevent the cold air from going down my dryer vent. I was having trouble with condensation developing on the vent and leaking on the floor. This solve that problem I would recommend it for anybody.

I read the lower than 3 star reviews before I purchased and I purchased anyway. Of course there was no instructions but I’m familiar with these things. This damper needs to be installed in the correct orientation. Hinged doors open to the outside. It needs to be connected to the existing 4” exhaust pipe with foil tape (ensure no leakage) on both sides with the spring hinge in a horizontal or vertical position. If you follow those simple rules this thing works great! My 50 CFM fan moved air with no issues and there is no air from the windy outside pushing back into the house. I would say that the closer you install this damper to the outside damper that is attached to your house, the better your results. I would buy this again. Correct installation is everything.

Great price Great product

I used two of these with my 4x4x4 foot generator enclosure to keep my 9kw inverter generator cool when running during power outages.