SHARPAL 115N Credit Card Size Diamond Sharpening Stone-Extra Fine 1200 Grit measures L 3 1\/4-inch x W 2 1\/8-inch x D .14-inch. Fits easily in pocket or wallet. Comes in convenient storage pouch. Industrial monocrystalline diamond Extra Fine 1200 grit (9 micron) is electroplated in nickel onto a steel base for longevity. It quickly hones and refines knives, small edged and pointed tools including carbide, high speed steel, titanium, ceramics and most any super hard material including the newer materials being used by most knife manufacturers. Sharpen dry. No messy oil needed. Patent pending ring grip holding protects hands from hurting when sharpen.