W8 Diamond Whetstones 200mm (8 in) are ideal for kitchen use and for the honing of smaller workshop tools. They have a large, wider diamond surface for sharpening a variety of knives and edges. They are supplied with a non-skid hardwood case, and tabs for permanent mounting are moulded into the stone's base. Black Extra Coarse Grade 220, 60 micron. Blue Coarse Grade 325, 45 micron. Red Fine Grade 600, 25 micron. Green Extra Fine Grade 1200, 9 micron. Green Extra Fine 1200g, 9 micron