correct me if I am wrong but I just checked this stuff out. I have a 26.8mm thompson post that I wanted to use on my 27.2mm. No one I could find has a shim to that size. Out of 3 different companies that make them, you can only get shims 25.2 on up and 27.2 on up. Again correct me if wrong. With that said I had a 26.8 that I used on my older 27.2 with the use of a strip of aluminum cut from a pop can and wrapped around the post. Worked like a charm and unless someone will buy the Thompson I will do that again. Mine didn't look nice but it worked.