flexible duct 1,fire-retardant PVC material 2,competitive price,fine quality 3,Oil, Acid, Alkai & high temperature Resistant flexible duct:/air ... duct,ventilating duct,flex duct, ventilation duct 1,Material: PVC flam-resistant static-free fabric with steel wire reinforced.2 ... to supply fresh air.keep more savely and effectively during working.with the strap or pp rope can conveniently connect to the ...