Product review (4 stars): Don't forget collar!
The only reason I took out one star is because even when I research items very carefully before making purchases, I still miss the fact that I need to add collar to interface hood to duct.

First I thought something missing from package. Apparently not. What you see is what you get. I thought it has step flange with option to put 3 or 4 " pipe in it. Not so. On the bottom there is only flat round hole 4 and 1/4" diameter. Any bare duct will fit loose. I end up stuffing foam around pipe's end and smudging it with a lot of silicone.

The hood itself is well made. A bit smaller than I expect, so check dimensions carefully.

And don't forget to order collar with it!