◆ Using advanced front double door opening device small wind resistance，good sealing，high efficiency，lengthened cone design improve exhaust power．

◆ Galvanized steel frame is made of 180g／㎡。galvanized layer avoid rust．

◆ Fan double doors closed with the rubber sealing which effectively avoid air backflow when start fans at different time．Greatly improve the operation efficency by 15-20％compared with the...