W8 double sided (combination) diamond whetstones will not break, chip, crack, hollow or groove. These ultra precision whetstones are lightweight and have a totally rigid construction. Use water for lubrication - no oil, smell or mess and can hone ALL hard materials: carbide, steel. The grits are denoted by a dual coloured circle which is set into one end. 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.The green side (Extra Fine) is suitable for general carpenters tools, wood flat bits, auger bits, garden tools, darts, fish hooks, masonry drills etc.The blue side (Coarse) is suitable for knives, woodworking tools, T/C tooling etc. Blue: Coarse 325g, 45 micronGreen: Extra Fine 1200g, 9 micron