Product review (4 stars): Great for round duct, inexpensive, range hood
If your home has a 7 inch round duct, this is a perfect fit. Just buy the damper, it slides right on top of the hood. I found that local big box stores had none of these smaller units with a round duct fitting. Only the 200$ units had a conversion piece for the round duct in stainless steel. I bought one only to return it because the expensive ones are too deep, it stuck way too far out. This is a great, inexpensive alternative for those who need stainless steel and a round duct.  I noticed spaces between the metal panels where light would shine through at the joint. I caulked them from the bottom and it's fine. Most people wouldn't even care.