DMT W4K 4-Inch Diamond Whetstone Deluxe Kit Of 4 Assorted Models (W4X, W4C, WMF, W4E) Superior diamond sharpening stones Legendary quality Made in the USA Handy fabric tool roll and assorted stones for sharpening convenience Four diamond grits in extra-coarse, coarse, fine and extra-fine 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