All IOXIO® knife sharpeners are made of aluminum oxide ceramic. They combine the hardness of the whetstone with the shape of the conventional sharpening steel. The ceramic grinding surface achieves an abrasion of material on the blade, sharpening it and reshaping it on the cutting edge. IOXIO® knife sharpeners are not coated. They are made of an all-ceramic sharpening rod and virtually do not wear out during sharpening.