Hart & Cooleys flexible insulated duct is listed as a class 1 air duct. This duct consists of a flexible helix core made of two-ply polyester laminate and corrosion-resistant galvanized wire. It is surrounded by a blanket of formaldehyde-free, fiberglass insulation, that helps to reduce heat and cool loss as well as jacketed by a heavy-duty, fire retardant, black polyethylene vapor barrier. Flexible insulated duct can be installed in place of galvanized pipe in most applications. In addition, due to its flexible nature, the need for elbows is eliminated, allowing for ease of installation in difficult to reach areas. This duct is ideal for use in general ventilation applications including heating, air conditioning, intake and exhaust.