ventilation duct fire-retardant PVC material competitive price,fine quality Oil, Acid, Alkai & high temperature Resistant ventilation duct/ flexible duct:/air duct/exhaust duct,ventilating duct,flex duct, air ducting, pvc ducting 1,Material: PVC flam-resistant static-free fabric with steel wire reinforced.2.PVC Thickness:0.3mm-0.45mm.3,Diameter:4" to 60" stander length:5m or 10m4,Main color: ...