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 Red side is suitable for all woodworking tools, carbide tooling, router bits, 3D bits etc.The Blue side is suitable for all general carpentry, tin snips, wood flat bits, augers, garden edge tools etc. Blue: Coarse 325g, 45 micronRed: Fine 600g, 25 micron