Product review (5 stars): Clean simple and much more attractive than a stack
For years we had long galvanized vents with large bird cage caps -- They were ugly.  We stripped the roof of shingles and put new shingles on with these roof vents for our range and bathroom fans extruding out the roof.  They are much more attractive or less eye catching.  We love the new look of our roof.  And we enjoy the idea that we have two flaps, One on the Broan-Nutone roof vent and one on the fan unit; this aids in keeping cold air out.  BUT, The low decibel fans are diminished because the air has less vertical space to travel; our fans are noisier due to these vents.