"Tiny Cooling Fan" bearings can be divided into the slide (oil) bearings and ball types. Lower prices and a sliding bearing fan rotation sound small, but low reliability. Cheap sliding bearing only one or a few small holes in the ring can add the oil, the fan motor to rotate in the ring, add lubricating oil in the pores know constantly lubricated bearings. Plain bearing made quickly disappear within a few months, so if "Tiny Cooling Fan" sliding bearings, life may be shorter, maintaining relatively some trouble. Some manufacturers use internal Teflon sliding bearings, which at the same time maintaining the original low-noise characteristics with the ball as high reliability, but this plain bearings price will be higher. Ball bearing is larger than the noise, the price is relatively expensive, but its higher reliability, universal life than the sliding "Tiny Cooling Fan" longer. Ball bearing fan can have a low coefficient of friction and wear rate, the better the ball bearings generally have a high MTBF (mean time between failure).