The Wusthof Classic Ikon 2-stage Stainless Steel Hand-Held Knife Sharpener produces a cutting angle of 14° on each side (28° total) suitable for sharpening all varieties of knives. The coarse diamond stage is recommended for dull and blunt knife blades, while the fine ceramic stage is suitable for finishing the edge after using the coarse stage or when you want to an edge that is already somewhat sharp. The ceramic slats grind the blade to regain its original sharpness. Knives with a serrated edge should only be sharpened using the Coarse stage in order to remove any burrs that may have developed. The blade of the knife is inserted vertically into the slot with the grinding slats. The rear end of the blade is placed between the slats and pulled gently through to the tip, keeping the blade straight, meanwhile, the handle of the device should be held with the other hand. The ergonomic handle and the non-slip base of the knife sharpener ensure safe handling. The process is repeated depending on the bluntness of the blade. In order to achieve the best possible result, the knife blades should be cleaned before and after every grinding process.