... sewn flexible ducting fire-retardant PVC material competitive price,fine quality Oil,Acid,Alkai &high temperature Resistant sewn flexible ducting/Ventilation hose/Flexible duct ... :/air duct/exhaust duct,ventilating duct,flex duct 1,Material: PVC flam- ... static-free fabric with steel wire reinforced.2.PVC Thickness:0.3mm-0.45mm.3,Diameter:4" ...