Great knives require great sharpeners. The Wusthof Precision Edge Diamond Electric Sharpener delivers a ultra sharp factory edge. The sharpener features interlocking diamond abrasive wheels. These wheels are crafted in the USA by Norton a long time leader in sharpening stones. These interlocking diamond wheels sharpen both sides of the knife at the same time quickly with minimal effort. The unit assures equal treatment of both sides of the knife blade for a true uniform edge. The Wusthof sharpener has two settings. The initial setting is for coarse grinding of nicked or damaged blades. The fine setting will easily restore you to a factory edge.