... -proof flexible ductanti-static ventilation duct, air duct, anti-static flexible ductflexible duct:/air duct/exhaust duct,ventilating duct,flex duct, ventilation duct1,Material: PVC ... 1pc of ring each 1.5m distance,can easily fix the duct at the stationary place.2.PVC Thickness:0.3mm ... alkali,oleic acid, harmful liquid state gas ect. the duct body is without any lapping defect,with the strong points ...