... exhaust pipe 1.high qulity,best price,prompt shipment 2.widely used in ventilation system 3.made of alum foil+steel Flexible exhaust ... ducts are specifically produced for low and medium pressure heating, cooling, ventilation, exhaust and air conditioning systems. ... ---not decay, mildew, durability.Fire---resistance.Practicality: suitable for the densely-populated area (such as school, supermarket, ...