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 is suitable for quality knives, woodworking tools, T/C tooling etc.The Red side is suitable for all woodworking tools, carbide tooling, router bits, 3D bits etc. Red: Fine 600g, 25 micronGreen: Extra Fine 1200g, 9 micron