The "220V Cooling Fan" drive motor is placed outside the box, or the entire circuit auxiliary section stealth (extended) in the frame, rather than the traditional axial section; the center bearing and retain only a key part of increasing the area over the air, Even more significantly reduced blind spots. The main improvement is the design of the magnet rotor and the stator windings - increasing the rotor ring size, set in the whole "220V Cooling Fan" fan outside, the stator windings are only two, mounted within the frame of the corner with the circuit portion . External magnetic design of the fan noise can be more of the same common axial "220V Cooling Fan" to increase the maximum static pressure of 10% -25% of the maximum amount of air. Personal recommendation: the manufacturing process is relatively complex, the cost is too high; do not use as well.