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 Red side is suitable for sharpening all woodworking tools, carbide tooling, router bits, 3D bits, woodworking and kitchen knives. The Blue side is suitable for sharpening general carpentry tools, tin snips, wood flat bits, Stanley knives, masonry drills, chisels, garden tools, fish hooks, darts etc. Blue: Coarse 325g, 45 micronRed: Fine 600g, 25 micron