Product review (4 stars): Works well.
If you're not super handy and have tin snips handy.....or...you don't want to hire someone to install this....stay away.  But It does do what it says.  It is not as flush to the wall as you might like.  I wish I had the exact distance for you, but it's installed in our barn in Arizona.  Originally we had one of the flex hose type and the dryer was heating up too much, and we feared a lint fire.  So...we bought this and installed it.
Works well, but I could not have put it in.  Hubby did it.