Product review (3 stars): Needs a bit of tweaking.
Opening for 4" vent pipe did not fit. I had to purchase new vent pipe that had corrugation at one end so that it would fit into the body. With only 1/2 inch to insert into the body, it's easy for the vent pipe to slip out (assuming it's not secured from the other side), and they don't provide holes to screw in the pipe so that it's secure. I had to do that myself. After having to purchase new vent pipe and make my own screw holes to secure the vent pipe, and mounting, it does work. It was just a pain to install and required an additional purchase.