I have a very small criticism of this tool. It consists of diamonds attached to one side of a square tube. Mine has a slightly crumpled tube so only the "corners" can actually make contact with the grinding wheel, while most diamonds never get close enough to make contact in the flat part of the work surface. That said, the tool still works and I've had no problem getting my wheels nice and flat. There are enough diamonds "connected by the edges" that I can do an efficient job even using less…