M-Ke Thermaflex Flexible Hvac Duct - 4 Inch Diameter R4.2

Thermaflex m-ke hvac ducts have a vinyl coated spring steel wire coil construction that is ideal for low, medium pressure heating and cooling environments. these highly efficient flex ducts feature a core that is bonded to the steel wire coil to support the fiberglass insulation. duct insulation is available in three different r-values for varied thickness r-4.2, r-6.0 and r-8.0. the acoustically rated, polyethylene inner liner on these hvac ducts eliminates noise and easily expands. spiral ducts are mold and mildew resistant. temperature range is from -20f to 200f and -20f to 250f intermittent. inner core is self-extinguishing. ducts measure 4-20" in diameter. greenguard certified. 10 year limited warranty.