Product details:

Highly efficient, Thermaflex G-KM spiral ducts are premium air vessels for low, medium pressure heating and cooling systems. These acoustically rated, HVAC ducts eliminate noise and feature a core that easily expands over fitting. The core is bonded to a steel wire coil to support the thick fiberglass insulation blanket. These air ducts feature a heavy duty polyethylene vapor barrier that provides even airflow and a double air seal. They are self-extinguishing and won't support flames. Temperature range is from -20F to 250F and -20F to 250F intermittent. Ducts have a 3-20" diameter. Greenguard certified.