Product review (5 stars): Juryrigged, but worked out fine!
Very happy with how easy it was to install this product.  I wasn't able to screw the "wall side" ring to the wall due to baseboard, a gas line, and a pipe that wasn't plumb inside the wall.  I used foil tape to make a tight connection on that side and used the clamp on the dryer side.  This resulted in a rock solid connection that is way better than the leaky periscope device that was back there before.