The DMT 70mm Mini-Stone is the perfect upgrade to any tool kit or outdoor gear. The 70mm Mini-Stones are small enough to be tossed in a backpack or tool kit or even put in your pocket. All DMT Mini Stones feature DMT's signature interrupted diamond surface polka-dot pattern. For proper tool maintenance, woodworkers, chefs and other professionals rely on the superior quality and versatility of DMT products. DMT's monocrystalline diamond surface sharpens knives faster than conventional stonesNo oil is needed-sharpen dry or with waterDurable construction will provide years of consistent performance and reliable serviceGrit Descriptions: Extra Coarse (60 micron / 220) when significant removal of material is needed for damaged edges.(Black)Coarse (45 micron / 325 mesh) to quickly restore a neglected edge. (Blue)Fine (25 micron / 600 mesh) for a razor sharp edge. (Red)Extra-Fine (9 micron / 1200 mesh) to polish and refine a razor edge after sharpening with a coarser diamond. (Green)