Product review (4 stars): Works well, might prove restrictive for a "fancy" dryer
I bought this thing because my new washer and dryer are about 4" deeper than my old set.  This puts them right at my laundry doors.  I was hoping this would give me the space to close the door.  It did just the trick.  You do need to make sure to buy some special tape to seal it all up or else you'll be getting extra moisture in your laundry room.  That was easy enough.  My only issue now is that my fancy dryer keeps telling me to "check for vent blockage."  It did this right after installing the periscope.  I'm not going to worry about it for now.  It is something to keep in mind though.