ATCO provides insulated flex duct with three different R-Values (4.2, 6.0, and 8.0). The thickness of each is:
R-4.2 = 1 ¼” C-Value of Approx: 0.238
R-6.0 = 2” C-Value of Approx: 0.167
R-8.0 = 2 ½” C-Value of Approx: 0.125

All fiberglass insulation is supplied by Owens Corning.

In an attempt to standardize, the flexible duct industry no longer states insulation values in thickness and density. The Air Diffusion Council, an industry organization of manufacturers, certifies R-Values based on insulation only, at installed wall thickness, based on ASTM C-518. Underwriters Laboratories classifies these tested R-Values based on plant inspections. These two third party verifications provide an accurate and reliable method of assuring that you are getting the thermal performance that you require.