Product review (4 stars): Quality vent made with heavy gauge steel but a little difficult to install
Like everyone says, this is well built with a heavy gauge steel and it's not going to bend.  The flap on mine doesn't seal perfectly to the included foam tape, but it may settle with time.  Using this vent has stopped the back flow drafts I've had been having.  I found the installation to be a little difficult because the tube is a fraction larger than a 4" hole saw.  I spent a good amount of time sanding the hole I had drilled with a 4" blade in order to get than to fit.  Overall a good product and I'm happy with the purchase.