Smith's DBSF Extra Wide Diamond Stone Fine Sharpener, 6" x 2-1/2"Multiple layers of micron sized moncrystalline diamonds bonded in nickel to a flat metal surface. The unique overlapping oval hole design speeds sharpening by collecting and holding the metal filings which ordinarily build up during the sharpening process. This allows the sharpening surface to remain clean and clear and speeds sharpening. This stone is excellent for sharpening wide woodworking tools, medium to small sport utility knives, or kitchen