This is a sharpening stone quarried in Finland, and is composed of quartz, feldspar, and mica. This stone is around 800-1000 grit. Has a groove for sharpening hooks. Measures 4 inches by 1 inch by 3/16 inches. Comes with a very nice carrying case with a belt loop, so it's always at your side when you need it. Makes a great gift for the camper / hunter / fisher in your life!