For accuracy: At first I thought that I would trust the thing not quite. We have then a small chamber measured in detail for the installation of shelves (which should match exactly). In short, it has worked amazingly well. We had not reground or even throw away, I would, if I would do it again, pull off anywhere yet 1-2mm, then it fits just a tad bit more detail. But for the device absolutely amazing and commendable.