Select Choose a good brand "220V Cooling Fan" means choosing quality, so that the DC fan is an important quality assurance from the brand. Choose from the outer surface should be considered as relatively thick, the color is pure from the appearance (especially black, the color of the fans is not important), at the edge of the box leaves no flash, see "220V Cooling Fan" blades Thickness (very important since too thin easily broken), there is no significant deformation when Yong Shounie frame. Cooling fan also choose from the bearing up because bearings are divided into two kinds of ball bearings and oil-bearing ball bearing long life, low noise, but the price is very expensive requirements. "220V Cooling Fan" oil-bearing ball bearing service life is shorter than 1/3, it may be some noise (over one year) in use for some time, but the price is cheap.