4" Knife Blade Sharpening Stone 2-Sided Fine & Coarse Grades Grit 400#/1500 This sharpening stone is made of extra-hard aluminum oxide, and is double sided with coarse grit and fine grit. The two grit values being: 400 and 1500. Materia: Alumina oxide plus carborundum composite stones Grit: Oriange 400/Grey 1500; Ideal size for bench work;Intended for sharpening all types of tools and knives Dimensions: 100mm x 35mm x 22mm (Appox 4" x 1.38" x 0.87")