What really concerns me about that Tesup model is 3-blade design with small air gap between blades. I have no idea how they think that would be more effective

What really concerns me about that Tesup model is 3-blade design with small air gap between blades. I have no idea how they think that would be more effective than 2-blade Savonius-principle rotor. It's possible to sell consumers ad-hoc designs that are unnecessarily inefficient just because they look cool.