... and lightweight.The products have been tested on fire resistanceAluminum Flexible DuctConstructed of a heavy duty 3-ply, aluminum foil ... laminate, encapsulating a high density, corrosion resistant wire helix, forming an air tight, easy to use, quality air connector. ... fan air vent ,roof ventilation , ventilator use ,And so on.Low costs on transport and logistic..No special tools required for ...