W8 Diamond Whetstones 200 mm. (8 in.) are ideal for kitchen use & for the honing of smaller workshop tools. They have a large wider diamond surface for sharpening a variety of knives & edges. It is supplied with a non-skid hardwood case & has tabs for permanent mounting are moulded into the stones 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 Black: Extra Coarse 220 g. 60 micron.