<https://www.htgsupply.com/products/4-inch-flexible-ducting/#product>
<http://schema.org/description>
"Mylar and wire construction for durability and maneuverability. Handles temperatures up to 140&deg;F and will not kink. Ducting has a diameter of 4\", and fits the standard 4\" flange. You choose between an 8' and 25' option."
<https://www.htgsupply.com/products/4-inch-flexible-ducting/>