How to identify Micro Cooling Fan?

See "Micro Cooling Fan" diameter fan blade twist angle and size: the larger inner diameter blades, the blades cutting the air volume air generated greater; the harder torsion angle increases cutting wind, the wind blowing out the hardness is large; the wind the more the number of leaves more intensive wind shear, wind effect softer, more stable air flow, generally five blades of fan blades inner diameter than the big three, and the twist angle of the three blades of more than five blades is large, it is five large amount of wind blades, the wind effect and soft, three blades wind speed, wind effect hard. Identification "Micro Cooling Fan" Blade Material good or bad: "Micro Cooling Fan" blades are made of a new material PP, AS new materials and recycled materials. First, we must learn to identify material or new material back: back to the material is processed by the injection of waste or expected from, there is a big smell, no environmental protection, low cost, becomes very brittle, fragile in cold weather, while not environmental protection.