... house appliance ,machine equipment etc.1.Performance: low noise, light vibration,strong cooling, muti-role, long ... 1.When we choose the fans ,not base on the speed, when the cooling efficiency are same ... , bearing wear and tear, friction coefficient is big, noise level is higher,and life shorter. 5.the wire ... (Detect fan speed value), water proof and so on.4.CEETIFICATE:CE: have been got the certificate ...