There are certain physical "Waterproof Cooling Fan" knowledge knows: the same pressure and the contact surface roughness of the situation, rolling friction is less than sliding friction. Wheels is one of the greatest invention is based on this theory and the birth of human beings, the ball bearing is a major example of the practical application of this theory. "Waterproof Cooling Fan" ball bearing lubricant no longer rely solely on filling the gap between the shaft and sleeve, but will slightly expand the space in which the placement of several metal balls. When the shaft and sleeve relative motion, the ball also will be rolling, not sliding friction with both reduce rotational resistance, reduce energy loss. Of course, in order to fill the space and sky lubrication, "Waterproof Cooling Fan" ball bearings also need to use a lubricant, but the work space is relatively oil-bearing seal better, and less friction, long life.