Product review (5 stars): It Works...
It works.  What's great about this system is there are no filters and multiple parts to clean and change.  Just one basic "maintenance free" box.  You take out the old, and the new one easily fits in the slot.  That's all there is to it.  Nothing more, nothing less.  It works fine and seems to last forever. (Of course, ours was quite dirty by the time I got around to changing it)