This Imperial Duct Insulation Sleeve works as an energy-efficient insulation blanket suitable for heating, ventilation, and air conditioning systems. Specifically designed to insulate rigid or semi-rigid round ducts, it is an excellent method for reducing heat or cool loss and condensation build-up. The sleeve is made of a thick fiberglass insulation blanket enclosed in a strong, fiberglass-reinforced silver metalized outer jacket. The insulation sleeve measures 8-in x 25-ft, meets UL 181 standards for Class 1 Air Duct, and features an energy-efficient insulation R-value of 6.0. Check your local building codes prior to installation. Insulation blanket designed for insulating rigid or semi-rigid round ducts Suitable for use with heating, ventilation, and air conditioning systems Helps reduce heat or cool loss and condensation for energy efficiency Meets UL 181 Class 1 Air Duct standards Thick fiberglass insulation blanket Heavy-duty silver metalized outer jacket Fiberglass insulation R-value: 6.0 Color/Finish Family: Silver Type: Flexible Diameter (Inches): 8.0 Maximum Length (Inches): 300.0 Duct Material: Polyester Insulated: Yes Insulation Material: Fiberglass Warranty: 1-year limited CA Residents: Prop 65 Warning(s): No R Value: 6.0 Safety Listing: UL safety listing UNSPSC: 72151200