Another decent indicator of a fan's capacity is the electrical draw of it's motor. Often the makers give this as a wattage rating. Obviously there are several factors that come into play with respect to the actual CFM the fan pushes. But for the most part the motor's "power" is related to the fan blade's workload. The CFR Performance site does not specify the motor's capacity, so this does not help in this case. By comparison, what is the CFM rating of the Spal 10" units? For the most part, Spal fans have a pretty high flow rating for the fan size. But that's not to say there aren't better ones out there.