DMT WS7K2 Mini Diamond Ski and Snowboard Stone - Kit of 3 Stones in Coarse, X Coarse, and XX Coarse Quick edge repair anywhere Three diamond stones in coarse, extra-coarse and extra-extra coarse Sharpens knives faster than conventional stones with DMT's monocrystalline diamond surface No oil is needed-sharpen dry or with water Durable construction will provide years of consistent performance and reliable service