"220V Cooling Fan" blades will present a matt surface effect, against the light, you can see the fine particles of uniform, hand feels is rough; more upscale fan blade material was often mixed with polyester fiber new fan blade surface can clearly see the fibers emerge lines generated at the surface. The renovation sector because of long friction with the air, "220V Cooling Fan" blade surface particles are not, become very smooth, do not see the fiber lines emerge, you will see a collision course out traces. "220V Cooling Fan" refurbished fan is used, so the mounting holes leaves a trace, if it is used it will leave the thread in the hole, if it is fixed with a screw nut plus screws on from work on Nuts will leave indentations around the hole.