DMT W250FCNB Double Sided Diamond Whetstone 250mm Fine / Coarse. This double-sided diamond whetstone will not break, chip, crack, hollow, or groove. It is ultra-precision, lightweight, and has a rigid construction. Use water for lubrication; no oil, smell, or mess. It can hone all hard materials, including carbide and steel. The grits are denoted by a dual-colored circle set into one end: Black for Extra Coarse (220 grit, 60 micron), Blue for Coarse (325 grit, 45 micron), Red for Fine (600 grit, 25 micron), and Green for Extra Fine (1200 grit, 9 micron). The 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, and chisels.