... Mining, Engineering Tunnel, Deep Well Super Steel Ring Air Duct for Engineering Tunnel Features: Application: Undergound Mining, Engineering Tunnel ... 400mm/ 450mm/ 500 mm/ 600mm/ 800mm/ 1000 /1200 mm Duct Length: 5m / 10m / 20m/ 30m Material: PVC fabric, super ... Grey /yellow Function: Antiflaming , Antistatic Super Steel Ring Air Duct parameters: Model Size (mm)Deviation Pipe diameter(mm)150 ...