1.low noise,big airfow 2.thick zinc coat,anti-rust, 3.low energy consumption 4.CE certificate ModelBladeDiameter/mmFrequency/HzCurrenc y/AInputPower/KwVoltage/vRotationalSpeed(r/min)Noise(db)Airflow(m3/h)Size/mmDB13801270(50in)502.81.13801440<=64510201380*1380*1300Features,This fan adopts advance oper system,butterfly type, with two semicircle shutter doors, wind resistance is small, good air- ...