Product review (3 stars): Works as intended, could be better quality
This product wasn't too terribly expensive and works as intended.  Others have commented about the small plastic "floating" piece on the inside hanging up, but mine moved up and down freely and seals tightly.  There is no mounting hardware included with the unit, which was fine with me because I doubt they'd send something I could use on concrete anyway.  The plastic it is constructed of is not the highest quality, so you have to be careful when installing not to crack it.  I wonder if this will hold up to the elements, and time will tell.  The top and bottom halves come apart which made the installation a little easier for me.  I installed against a concrete foundation, so I just used some concrete anchors and some silicone sealant.  Again, careful with tightening the anchors to the unit.  I heard it crunching a little, so I backed off so it didn't crack.

I've used the dryer several times and so far so good.  My dryer vents comes out under my deck, so it is relatively protected from the elements.  If it lasts me 5 years, I'll be more than satisfied.