I think this is what it is. I know the minimum size is 13 mm and open till I belive 50 mm, seems like it is. But it is perfectly fit in our sleeves. There is two kind, one is Aluminium oxise and other is Silicon Carbide. I am using aluminium oxide-it is softer and doesn't hirt chrome. Silicon cirbide will scratch chrome. It costs like $ 15.
Just insert it in sleeve and turn around 3-4 times-it is ready.