Product review (5 stars): I think it's pretty stupid that the industry is inconsistent
Replaced this same brand from 20 years ago. DEFLECTO  It is odd because I recently returned several hoods to the big box hardware stores because theirs fit a 4" pipe assuming the pipe coming out the wall is crimped.  This one assumes it comes straight out uncrimped as mine is.  I think it's pretty stupid that the industry is inconsistent.  The problem is you can't just pull the pipe out of the wall because the mortar is part of it as it goes thru the brick wall and you can't just add a short piece because then it would stick out too far and look stupid.  This was super cheap and the quality is cheap as well.  I would be willing to pay more for higher quality.  The old vent the flap became warped and I am sure this will in time.  Probably ought to buy two or three more.  Thanks anyway for still making the same design and it fits nearly as well.