Prefabricated Ductwork (INSULATED FLEXIBLE DUCTWORK) (Product availablity is subject to change without notice. Not all products are available from all facilities.) METALIZED R6.0 INSULATED FLEXIBLE DUCT (F6IFD SERIES) • Metalized jacket. • 2" glass fiber -R-Value 6.0 Click here to print a Detailed Specification Sheet (PDF) BLACK JACKET R8.0 INSULATED FLEXIBLE DUCT (8IFD SERIES) • Black polyethylene jacket. • 3" glass fiber -R-Value 8.0 Click here to print a Detailed Specification Sheet (PDF)