Product review (3 stars): It does work, however there are holes in it.
Like many others said, this is very thin flexible ducting. Sure it works fine. If 100% leak-proof is what you need, DON'T BUY. If you are using this indoors in a greenhouse I would say its not much of an issue. The price is great for how much you get. I would say once this is installed don't take it down and re-install it somewhere else as the aluminum will start to flake apart. Would I buy it again? Probably not.