Ceramics are used in all types of sharpeners. Handheld, rods, bench stones and whetstones. They are fast, easy and effective for maintaining your knives edge. Ceramic material has the hardness of glass which is much harder than steel. But unlike glass, ceramic is abrasive. And it is this combination of abrasive hardness that makes ceramic such a good knife sharpener. Most ceramics are fragile if dropped on a hard surface. They remove a microscopic amount of steel just enough to straighten the edge until you need to do a more intensive sharpening routine. I personally use religiously when I need to quickly place a sharp edge on a somewhat dull edge until I am ready to give my knives a proper sharpening.