Our #400 grit Super Ceramic Water Stone is designed primarily for rapid sharpening of stainless steel, high alloy steel and blue steel edges that are difficult to sharpen with other synthetic water stones. The sharpening action is very similar to a natural stone in that the surface has a bit of elasticity that keeps the tool from skidding. A 2-5/8˝ x 2˝ x 1¼˝ Nagura is included with each Super Ceramic Water Stone. Complete instructions for care and use are included. Their size is 8¼˝ x 2¾˝ x 1˝ and are mounted on a plastic base.