Stop in for a cup of coffee

Does anyone know what kind of hose that used between the heater and the defroster vents on a 65 Dart ?

I am picturing some kind of flexible corrugated aluminum hose. But I can not find anything in 2.5 inch, which is the size of the defroster vents. I find 2 inch, and then I find 4 inch, and a few in 3 inch.

I am aware of that the heater outlets are smaller than 2.5 inches.

Bill