... as tunnel, basement, ship building or welding, laboratory ,air-conditioner. flexible duct:/air duct/exhaust duct,ventilating duct,flex duct1,Material ... -resistant static-free fabric with steel wire reinforced.2.PVC Thickness:0.3mm-0.45mm.3,Diameter:4" to 60" ... portable ventilator to use together. good quality portable ventilator with pvc flexible duct for industry project