"Waterproof Cooling Fan" is commonly used bearings: ball bearings, oil bearing.
"Waterproof Cooling Fan" Ball Bearings: Ball (Ball Bearing) has changed the way the bearing friction, rolling friction, two hoop middle of some balls or steel columns, supplemented by some grease. This method is more effective in reducing the friction between the bearing surface phenomena, effectively increasing the fan bearing life, and therefore reduces the heat sink, longer life. The disadvantage is that the process brought about more complex, resulting in the cost of upgrading, but it also brings higher operating noise.
"Waterproof Cooling Fan" oil bearing: Bearing (Sleeve Bearing) is the use of sliding friction sleeve bearings, use of lubricants as a lubricant and DRA. You can say that the market is now the most common type of bearing technology, because of its low cost, simple to manufacture many products, including well-known brands have continued in use. The advantage is that when you use the initial quiet, low noise, low prices.