Smith's 4" Diamond Combination Bench Stone features coarse and fine grit sharpening surfaces. The surface contains multiple layers of micron-sized moncrystalline diamonds and a unique sharpening surface with an overlapping oval hole design. Each stone has a "micro-tool sharpening pad" and a sharpening groove for fish hooks or pointed tools. Features a soft grip rubber handle is to make sharpening safe and easy, thumb guard and you can store your stones in the handle for safekeeping.