What is Transition Duct?
The one flexible section permitted in a dryer exhaust. It must be a listed transition duct, a single unbroken length no longer than 8 feet, and it must remain visible — it cannot be concealed or pass through a wall. Generic foil hose sold alongside it is not the same product. In practice this is the most commonly damaged part of the whole system, because it gets crushed when the dryer is pushed back against the wall.
