... ideal for difficult installs we have four kinds of Aluminium flexible duct ,the duct mainly engaged in ventilationsystem, like bathroom and ... system,HVAC , rang hood ,clothes dryer vent ,inline fan air vent ,roof ventilation , ventilator use ,And so on.Low ... exhaust applications including bathroom fans , furnace mounted humidifier units, air conditioning and ventilation system.Diameters 3” to 29” (75 ...