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 (Extra Fine) is suitable for general carpenters tools, wood flat bits, auger bits, garden tools, darts, fish hooks, masonry drills etc. The blue side (Coarse) is suitable for knives, woodworking tools, T/C tooling etc. Blue Coarse 325g, 45 micron Green Extra Fine 1200g, 9 micron