Ventilation Systems, Air Curtain Machine, Erv manufacturer / supplier in China, offering High Efficiency Box Type Silent Centrifugal Fan for Hotels Duct Mount with High Air Volume, Commercial Centrifugal Inline Fan High Efficiency Large Air Volume Centrifugal Fan 220V/380V, 220V Centrifugal Duct Fan Ball Cast Iron Roof Hotel Fresh Air Exhaust High Air Volume and so on.