It is understood that "Micro Cooling Fan" Speed is the number of revolutions per minute of the fan blades, the unit is rpm. Fan speed is determined by the motor inside the coil turns, voltage, number of fan blades, angle, height, diameter and bearing systems. Fan speed and quality are not necessarily linked. "Micro Cooling Fan" can be measured by the rotational speed of the internal speed signal, it can also be measured by the external. With the application of the ambient temperature changes, sometimes it requires a different fan speed to meet demand. Some vendors specially designed adjustable "Micro Cooling Fan" speed cooling fan, manual and automatic modes. Manual is designed to allow users to use low speed in winter to obtain a low noise, high speed to get a good cooling effect in the summer.