This Imperial Insulated Flexible Duct is ideal for use with heating, ventilation, and air conditioning systems. Its 2-ply polyester laminated inner core is constructed with supportive, non-corrosive coated wire. A blanket of fiberglass insulation surrounds the core which helps to reduce heat loss and condensation, and a silver metalized outer jacket with reinforced scrim surrounds the fiberglass insulation for durability. Because of its flexible nature, this duct can be installed in hard-to-reach areas without the need for elbows. The easy-to-install flexible polyester duct is intended for use wherever UL 181 standards for Class 1 Air Duct is required. It measures 7-in x 25-ft and features an insulation R-value of 6.0. Check your local building codes prior to installation. Suitable for use with heating, ventilation, and air conditioning systems Meets UL 181 Class 1 Air Duct standards 2-ply polyester laminated inner core constructed with non-corrosive coated wire Blanket of fiberglass insulation helps reduce heat cool loss and condensation Silver outer jacket with reinforced scrim for durability Eliminates the need for elbows, for ease of installation in hard-to-reach areas Oversized core for a seamless fit on collars and register boxes Fiberglass insulation R-value: 6.0 Color/Finish Family: Silver Type: Flexible Diameter (Inches): 7 Maximum Length (Inches): 300 Duct Material: Polyester Insulated: Yes Insulation Material: Fiberglass CA Residents: Prop 65 Warning(s): No R Value: 6 Safety Listing: UL safety listing Warranty: 1-year limited UNSPSC: 72151200