You might also try local HVAC shops. I went to the company that installed the HVAC in my house and asked them if they had 1" fiberglass duct liner. He took me into the shop and he had 5-6 rolls of Knauf. I had studied the chart at Bob Golds' site and knew this was an acceptable product. Might have paid more, but I was able to take it home right then. There were also a couple of HVAC supply shops in the area, but I wasn't sure about the performance of the fiberglass they carried. The main thing is, ask for "duct liner" and if they have it, ask the brand. Don't get stuck on a specific brand.