DMT WMC 4-Inch Machinist Diamond Whetstone With 1" Continuous Diamond Area - Coarse Superior diamond sharpening stones Legendary quality Made in the USA Versatile, portable sharpener for home or shop use 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