DMT W250ECNB 10-Inch DuoSharp Bench Stone Extra-Fine / Coarse Superior diamond sharpening stones Legendary quality Made in the USA Precision flat, two diamond surfaced sharpener guaranteed to provide consistent, even sharpening every time Two sided: Extra-Fine diamond to polish and refine an edge and Coarse diamond to transform a dull edge 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