Gray Flex 12-4GF-8_BAG Silver Insulated Flex Duct R8 12 Inches X 25 Feet

Product Description

The Gray Flex 12-4GF-8_BAG is a 12-inch diameter, R8-rated insulated flexible air duct sold in a 25-foot bag. It is designed for use in residential and commercial HVAC systems where high thermal performance and code compliance are required. HVAC technicians and mechanical contractors rely on this type of insulated flex duct to connect air handlers, plenums, and diffusers while minimizing heat gain or loss through the duct wall. The R8 insulation value makes this duct suitable for installations in unconditioned spaces such as attics, crawl spaces, and mechanical rooms where energy code requirements mandate higher thermal resistance. The Gray Flex 4GF-8 series is tested in accordance with U.L. 181 and approved for use as a Class 1 air duct material. This means it meets strict fire, smoke, and performance standards recognized by building codes across the country. The outer jacket is a scrim-reinforced metalized polyester vapor barrier that resists moisture intrusion and reflects radiant heat. The jacketing is printed with a certification label, foot markers, size, and performance data every 24 inches, with foot markers every 12 inches, making field measurement and inspection straightforward. The fiberglass insulation layer on the 4GF-8 model is a minimum of 2 and 5/8 inches thick, delivering the full R8 thermal resistance needed for energy-efficient duct systems. At the center of the duct is Gray Flex's exclusive patented reinforced inner liner, which creates an airtight core that reduces air leakage and maintains consistent airflow through the system. The duct handles a maximum operating temperature range of -20F to 250F, making it reliable across a wide range of climate conditions and system types. The maximum pressure rating is 10 inches positive and 3/4 inches W.G. negative per U.L. 181 standards. The fire rating meets a maximum flame spread of 25 and maximum smoke developed of 50, keeping the installation within Class 1 duct requirements. This flexible duct is a dependable choice for new construction, HVAC replacement projects, and system retrofits where insulated ductwork with proven performance ratings is needed.

• U.L. 181 tested and approved as a Class 1 air duct material for residential and commercial HVAC installations
• R8 insulation rating with a minimum 2 and 5/8 inches thick fiberglass insulation layer for superior thermal performance in unconditioned spaces
• Scrim-reinforced metalized polyester vapor barrier outer jacket with printed foot markers and certification data every 24 inches for easy field use

Product Highlights

The Gray Flex 12-4GF-8_BAG delivers R8 thermal resistance and U.L. 181 Class 1 compliance in a 12-inch insulated flexible duct, built for professional HVAC installations requiring high efficiency and code-approved performance.

Product Information

Standard Information

• Brand: GRAY FLEX
• Manufacturer Part Number: 12-4GF-8_BAG

Technical Specifications

• Flex Type: Insulated
• Inside Diameter: 12 inches
• R-Value: R8
• Insulated: Yes
• Core Material: Exclusive patented reinforced inner liner
• Maximum Temperature: -20F to 250F (-28.89C to 121.11C)
• Operating Temperature Range: -20F to 250F (-28.8C to 121.1C)
• Maximum Pressure: 10 inches positive, 3/4 inches W.G. negative
• Pressure Rating: 10 inches positive, 3/4 inches W.G. negative per U.L. 181
• Fire Rating: Maximum flame spread: 25; Maximum smoke developed: 50
• UPC: 687410304319