This is interesting, I remember doing tests quite a while ago with several fans stacked(different speeds, different diams) but never thought to try mounting the blades like this. I wonder how the noise/air flow compared to a reg 90mm fan?
At first when I looked at this I thought 2 separate spinning fans but after closer looking the 2 fans are attached together making 1 blade.
I dont get the reverse spinning thing though, 30sec isant gonna remove a significant amount of dust, that seems like adding complexity where it isant needed (marketing baloney)
Still it would be cool to compare this fan directly to a reg one..
Buy tin snips FIRST!