Product review (5 stars): Keeps it warm when it's cold
We live in Alaska.  The laundry room would stay cold in the winter, especially around the dryer.  If you didn't take the cloths out right away, they would be freezing.  After this was installed, everything stayed warm.

There is a cup inside that bucket you see on the photo that travels up and down with the dryer air.  When the dryer is off, the cup sits nicely on the curved pipe you see, blocking any air from entering the house.  It's also guarded by the bucket so wind won't dislodge it.  When the air is on, the cap goes up the bucket a ways and the air vents out the bottom of the bucket.  The top lid comes off so you can clean if you like.

  My installation didn't go as easy as some have written, but that is not the fault of this product, just different holes and needed an extension pipe.  Also the inlet to the dryer vent was exactly the same size as the pipe coming out of the house, so the pipe had to be crimped to fit inside dryer vent, not a big deal.

 Painted it the same color as the house. The instructions say to use latex paint on it, and it takes the paint well.

 In all a very good product.