Openings or guide lines on the blades increase, the main purpose is to reduce the vibration caused by the blades due to the airflow. Of course, it reduces vibration, noise will be decreased, the air will flow more smoothly in accordance with a predetermined flow, achieve better cooling effect. If you want while improving "220V Cooling Fan" of the air volume and pressure, then in addition to the blade design, by increasing the speed of the method it is relatively simple. However, the ensuing sound of wind shear blades rotating at high speed and bearing friction and other acoustic noise problem is troublesome people.