... 502.81.13801440<=64510201380*1380*1300Features,This fan adopts advance oper system,butterfly type, with two semicircle shutter doors, ... labor is reduced, also improve aesthetic result of fan When the two semicircle shutter doors close, the ... of galvanized coat is 180g/m29.Rim: al-alloy10.Fan cowl: galvanized sheet. Thickness is 1mm.12.Motor ... of charge during this period 50 inch butterfly exhaust fan