1.new design,based on air moving theory 2.Simple out looking,easy to be install. 3.Low noise. 4.Energy save. 5.light weight. Circular inline duct fan housing SIZEACV/HzWArpmm³/hPadBkgGDF100230/50600.182550170-4072-251483GDF125620.252550200-7572-227483GDF150640.262550350-12073-252494GDF160720.292500390-10068-261494GDF2001010.452550600-100142-451524.5GDF2501560.732450700-200135-376525GDF3152250. ...