MF-07R8 (7' length) flexible duct is constructed with a spring steel wire helix, encapsulated in a 2-ply, air tight inner-core. A universal male / female collar is factory attached to each end. R8 fiberglass insulation encompasses the core and a unique metalized, reinforced vapor barrier surrounds the entire duct.Features and Benefits: Collars sealed with UL-181 FX tape 10 year limited warranty Unique reinforced, metalized vapor barrier Guaranteed out of package length Certified R8 insulation GREENGUARD Gold Certification Formaldehyde Free