I am not sure what the actual name of the adapter material is. A close friend of mine got it from Gulf Wandes corp. and was told that it was PVC and would withstand 2000 degrees F. It was about a foot square scrap piece I believe, and cost him about $12.00. It was about 1 3/4" thick. He gave me enough to make a couple of the spacers. It Machines very good with no melting and does not cling to the milling cutter. We are going to go back and try to get some more.

Charlie W5RA