The knife sharpener features two stages, depending on how much the cutting performance has diminished. The first stage, "Coarse," is recommended when the knife is dull. The diamond-coated grinding wheels in the sharpener restore the edge angle. The second stage, "Fine," is suitable for honing after the first stage as well as for regular touch-ups of the blade. The ceramic rods smooth the edge, allowing the knife to regain its original sharpness. Knives with a serrated edge should only be sharpened with the second stage to remove the resulting burr. The traditional Solingen company has designed the knife sharpener so that even novices can easily sharpen their knives. Since the device sets a grinding angle of around 30 degrees, a wide variety of knives can be perfectly sharpened. Before and after each sharpening process, the knife blades should be cleaned to achieve optimal results.