"Waterproof Cooling Fan" the longest life expectancy, cost expensive; secondly copper clad aluminum, aluminum motor again. The best way to identify the movement material is a metal measuring instrument, but in general it is difficult to achieve, the conventional method of soil is the most direct: a look! Look at the movement of colors, open motor see movement color, "Waterproof Cooling Fan" is the core component of the motor movement, movement material there are many, but most of the material available in the market used are: copper movement, movement and copper clad aluminum wire movement. Copper Movement highest permeability, and attenuation coefficient is small, by color directly discriminated whether the movement is aluminum; two rub! Rub the surface movement, CCA was repeatedly wiping movement under the surface of copper will drop, after falling in the surface layers of silver, compared with copper clad aluminum motor movement; three weigh! "Waterproof Cooling Fan" find the same type of motor, the motor housing removed, the motor is greater than the weight of pure copper and copper clad aluminum motor motor.