The Shapton Glass Diamond Lapping Plate is the foundation of any sharpening system. Since the surface of the tool will mirror the stone it was sharpened on, is critical that the sharpening stone be flat. The Shapton Diamond Glass Lapping Plate is flat to within 5 microns, and will easily return Shapton stones to perfect flatness.Keeping your stones flat means sharper tools, but it will also ensure even wear for a longer stone life. Works with the whole Shapton line, both the Pro series and the Glass Stones.