Product review (1 stars): Leaks like a sieve
Maybe I got a bad one, but this thing leaks like a sieve.  I installed it on an existing roof, and I've installed similar vents before.  The roof pitch is 6 in 12, so fairly steep.  After installing I waited a day and then soaked the area using a hose.  Water poured into the inside of the duct.  This means that the flashing was good and I had properly flashed it to keep water from getting under the flange and around the duct hole.  The problem is that the uphill seam on this are not soldered or sealed in any way.  Water seeped in through the bottom seam along the uphill side, into a small gutter around the 6 inch vent, and then down the vent hole.  I could not believe how poorly it was designed/manufactured.  I didn't want to remove roofing and pull the nails, so I sealed the uphill seam with silicon and put a piece of aluminum flashing along the seam to protect the silicon.  DO NOT BUY THIS.  It isn't worth the hassle.  There are plenty of other vents on the market that have sealed seams.