advantage:high resistant to corrosion,long life and high tensile,easy installation,no nosie,no energy cost. 1, curved blades is scientifically the best results of the calculation can be strictly guaranteed state will never let rainwater intrusion. Ventilation, high efficiency, as long as not less than 0.2 meters in the breeze, or room with the outdoor temperature differences of more than 0.5 °C, ...
