Sharpening StoneHAIDU is one of the highest quality ceramic sharpening stone on the market. They come in many different grits from 250 up to 8000. All of them are very sturdy, even with frequent use, you can use these for years. The stones can be used dry, with oil or water which is probably the most effective. The stones are the most effective after 2 3 uses. We enclose a detailed tutorial for your order to use and clean your stones. Grits: 250, 600, 1000, 3000,