4" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 4” Ducting in Range Hoods and Bathrooms Fans

I needed some sort of back draft prevention for my bathroom vent fan setup because I was getting bugs and draft in my basement bathroom. These fit right up to other 4 inch ducting, and I used rubber connectors to secure these on. They look sleek, work great, and they have a great quality seal and don't let air back in. They have a double flap to prevent back drafting. I used two of them in my set up to keep each line isolated before a combining y connection

Well made. I use it for water fall spray booth and fits mine easy. I do have to use weather sealing tape to secure it to my booth.

I needed to create an exhaust system for my 3D printer so I purchased the AC Infinity cloud line in-line fan along with this backdraft damper since my exhaust leads directly outdoors. One thing I noticed is that the springs on this damper are pretty stiff so it requires a decent amount of airflow to push the damper flaps open. Using the cloud line S4's speed controller as a reference, the flaps didn't open until I got to level 4. The reason this may be an issue is because in temperature controlled environments (like printing certain types of material) you don't want your in-line fan to be too strong otherwise it will cool your chamber too quickly. Aside from that, the damper is constructed well and will likely last a long time. One other thing to note, I bought the 4" damper and with 4" ducting it is a very tight fit to get the ducting around so it does create a decent enough seal. Overall works well but if you only require a low airflow system like me I would recommend testing this out first before fully installing.

Quality is great, and worth the purchase. I wish it was a bit lighter like 3d print

If I could give it 6 stars, I would. This is my FOURTH go around at trying to solve a backdraft problem with my kitchen vent hood. This one finally did the trick. Amazing how many bad options there are out there for a backdraft damper, never would have guessed it. The problem is that most other backdraft preventer work by closing the flap using gravity alone, and it turns out that once installed, that's not always enough - kind of random. But you can tell right away when you step in the kitchen if the flap is open or not by whether youre freezing or comfortable: Walk to the hood; put your hand under and feel for the draft; get your answer - you'll always guess it right. With this one, it's always closed and the room is always comfortable. Thank you thank you thank you!! It's also very well made (sturdy, compared to all the others) and _not_ more expensive! It's also quieter than the others. Go figure. My only complaint: it only comes in 6" or 8" dia. WTF!! A vent hood has standard 7" ductwork. I got around this by buying and installing 2 flares, one on either sides. It mates nicely with the 7", but you need to have a bit of room in the cabinet above the hood: can't have a 90deg turn too close to the hood. You won't be able to cut through the metal work to reshape it easily, unless other thin-gage dampers, which I spent hours re-shaping. Works like a charm when installed right.

Little tricky install on my bathroom ceiling fan

After reading through dozens of reviews and product information, we first bought the AC Infinity Flexible 6-Inch Aluminum Ducting, Heavy-Duty Four-Layer Protection, 8-Feet Long for Heating Cooling Ventilation and Exhaust. It was packaged so well you could send it as a Christmas gift, the quality of the duct tubing was outstanding. Fast forward a week while we were installing the new stove exhaust fan, we realized we would need this flapper piece, as the old one was getting stuck. We were so impressed with the duct tubing that we purchased this product from AC as well, and were not disappointed. It is the Mercedes of exhaust flappers. This AC flapper was the exact size advertised at 5.79" width/diameter, which was just a smidgen smaller than most of the others advertised at 5.90" diameter. So instead of having to monkey around with it, it slipped perfectly inside the Vikio range hood 30" under cabinet kitchen hood with 980 CFM, 3 speed gesture sensing & touch control panel in stainless steel, vent hole on top the hood. A little larger it would not have worked, we are grateful the AC specs are perfect, it made the install a dream come true. I do agree with another review I read, in that the AC 6" ducting is a tight fit on their own product/flapper, although I got it to slip on, it was as tight as could be without being unworkable, but the bottom line is it went on. And it slipped over the existing 6" coupling tube to the roof perfectly. We will keep this company in mind when doing other projects, such as heating, vents, dryer etc, well worth the cost. Thank you

Works perfectly! Not too easy to open that it's flopping around but easy enough a light push my from acinfinity fan vents all these spores outside!