Here you can see the twelve blades better on the UFO. The bottom of the fan has a set of stationary fins designed to direct the air downward. This concept is similar to the Vantec Tornado fans.
Here's a nice first for an aftermarket fan, an 80mm to 92mm fan adapter. Basically if you don't know what this is, it allows you to use the bigger 90mm UFO fan on your 80mm sized heatsink.
Now Thermaltake could have gone cheap and made the fan adapter out of plastic, but they decided on making them out of aluminum.
This is nice as a plastic one could in the rare off chance crack if you tighten the screws to much.