... , ship building or welding, laboratory ,air-conditioner. flexible duct:/air duct/exhaust duct,ventilating duct,flex duct1,Material: PVC flam-resistant static-free fabric with steel ... .PVC Thickness:0.3mm-0.45mm.3,Diameter:4" to 60" stander length:5m or 10m4,Main color: yellow,red,orange .white ...