Product review (4 stars): Great design, but not air-tight.
Design is great for tight spaces, and keeps an open path for the air to exhaust.

I want to give it 5 stars, but I was disappointed that the elbow leaks tiny jets of air at a couple of its seams.  I recommend turning your dryer on, after installing, just to check for such leaks, before you push your dryer back towards the wall.  I ended up purchasing some aluminum tape, specifically designed for heated duct work, and wrapped all of the seams on the vent elbow, as well as where it connected to the longer hose.  This sealed the tiny leaks, and the system works great.

Also, when you replace this hose, take the opportunity to clean out any venting inside your wall.  Mine was coated with a heavy layer of lint, which I found out was constricting airflow to the outside.  Pretty scary stuff.