W10 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 micronBlue: Coarse Grade 325, 45 micronRed: Fine Grade 600, 25 micronGreen: Extra Fine Grade 1200, 9 micronThe Blue side is suitable for general carpentry tools, tinsnips, side cutters, wood bits, garden tools etc. The Black is suitable for damaged woodworking tools, cold chisels, axes, lawn edgers etc. Black: Extra Coarse 220g, 60 micronBlue: Coarse 325g, 45 micron