Builders Best® Foil Duct, Flexible, Multi-Ply, 25 feet Length, 4 Inch Dia, Aluminum/Polyester Laminate, Metalized Polyester, 6 Inch WG Positive, 3/4 WG Inch Negative, -20 to 180 deg FBuilders Best® Foil Duct, Flexible, Multi-Ply, 25 feet Length, 4 Inch Dia, Aluminum/Polyester Laminate, Metalized Polyester, 6 Inch WG Positive, 3/4 WG Inch Negative, -20 to 180 deg F