22mm is a stupid size IMO as most thick walled bangers are 3mm which will leave a 2mm gap which is 1mm too much (insert will move around too much, and cause more banger maintenance IME). It works, but when I went to 1mm gap from 2mm, I was quite happy about the better fitment, but i'm also quite picky.
18mm makes much more sense as you would have a textbook fit gap of 1mm with a 3mm thick walled like a Toro Grail. And the 18mm can handle large dabs (.1g) without a problem.
The hunt is on for the 3.5mm walled banger!