Dia-Sharp credit card-sized stones are lightweight and small (3.25"x2"x.05") to fit easily in a wallet, pocket or backpack for quick sharpening anywhere. Sharpen dry or with water - no oil required. Sharpening with DMT's monocrystalline diamond surface is faster than conventional stones and sharpens a wide variety of knives. Each Dia-Sharp credit card-sized sharpener comes in a vinyl color-coded slip case.