"DC Fan" refers to the amount of wind or air exhaust fan included in the total volume per minute, if calculated according to cubic feet, the unit is the amount of wind CFM; if you press m to count, that is CMM. Air flow cooling fan units often use the CFM (about 0.028 m3 / min). Wind is the most important indicator to measure the cooling capacity of the cooling fan. Obviously, the greater the amount of air cooling fan its cooling capacity is also higher. This is because the heat capacity of the air ratio is constant, the greater the amount of wind, that is, more air per unit of time can take away more heat. Of course, the same amount of wind cooling effect of wind flow situation the way.