Thermaflex flexible duct assemblies are thermally insulated, fully lined, and designed for efficient installation in low and medium pressure HVAC systems. Assemblies are 7 feet in length and are available in M-KC, M-KE and KM insulated products. Assemblies have galvanized male and female fittings attached to the inner core and outer vapor barrier. These units are especially suited for modular buildings and air distribution systems. They are affordable and convenient for jobs requiring large quantities of duplicated standardized preassembled air system connectors. These assemblies are available in standard insulation values of R-4.2, R-6.0 and R-8.0. Diameters range from 4" through 20" (R-4.2 and R-6.0) and from 5" through 20" (R-8.0).