The Rip Stop Silver Jacket Flex Duct has a metallic, polyester-vapor barrier with a special "rip-stop" scrim reinforcement. It also uses Johns Manville Formaldehyde-free insulation, which helps reduce overall formaldehyde exposure.
Johns Manville Formaldehyde-free fiberglass insulation|Galvanized or bronze metal core reinforcing|Oversized core to fit on collars and register boxes|Easy-to-carry package: up to 10 in bags are strapped to form a pair|Weather resistant packaging|Color coded packaging|Bar coded product labels|Polyester core/metalized polyester vapor barrier
Quietflex Flexible Duct, Rip Stop Insulated, Series: 80 Series, 10 in Inside Dia, 25 ft Length, 6000 fpm, R6 Insulation Value, <=0.05 perm Vapor Transmission, -1/2 to 10 in-WC, -20 to 180 deg F, Polyester/Fiberglass/Metalized Polyester, Silver, Domestic