Repa Market 4 Inch Backdraft Damper – Galvanized Steel Draft Blocker/One-Way Airflow Vent Stopper/HVAC Exhaust Dryer Duct Connector – Inline Spring-Loaded Backflow Preventer for Secure Ventilation

Hooked up inline with our hood fan above our stove, prevented back draft of cold air in the winter season. Easy install

Living in the deep south, after installing a new kitchen exhaust fan the down-draft from the attic was overwhelming. Especially since kitchen exhaust fans are located right over the stove and it is canning season! This item is wonderful. There is no more down-draft at all and combined with my wonderful new exhaust fan my kitchen is comfortable again. At least as comfortable as it can be when I am canning in the summer time in the deep south ;) Great product, shipping time was fast, installation was easy. Thank you!

This damper works, but the spring is very weak. If you tip it anywhere past horizontal the doors fall open, so it can only be installed with the doors facing up or horizontally. Additionally if the doors open all the way to the center, the springs are not strong enough to push them closed again. I haven't run into an issue with this yet, but just noticed during the installation and will need to check at some point to make sure they are not stuck open.

Perfect, really does what it is meant to do. I have two bathrooms that I connected to the same exit vent with a y connection, and noticed that when one bathroom vent was on, the other would get some of the air going out. I put these in and neither bathroom gets the back flow any more.

Well made and blocker plates (2 half moon pieces) pivot well for exhaust under lower pressures, and allows very minimal backdraft air to enter.

This thing was not functional out of the bag. It looked used. The springs were on backwards so the flaps would not stay closed. This 5 inch damper has 2 springs and when in the correct way are a bit stiff. It does work but it wasn't plug and play.

Worked great. As described.

Had an issue with hot are back drafting through my bathroom exhaust vents during the summer time and cold air coming through in the winter time! These stopped that issue. Seal in the inside ensures unwanted air stays out of areas you don’t want it