The DMT DiaSharp 10x4 fine/coarse is a large double-sided diamond sharpening stone. The coarse side is to sharpen your blunt knife and the fine side is the next step to achieve a razor-sharp edge. Diamond-coated sharpening stones quickly remove material and, depending on the grain size, sharpen your knives to razor-sharpness. This DMT DiaSharp Bench Stone is quite large in size, which makes it suitable for all types of knives, including large kitchen knives. The advantage of diamond sharpening stones is that they don't have to be lapped. For this DiaSharp stone, the diamond particles were added to a 9 mm thick steel sheet. As such, the flatness of this sharpening stone is guaranteed.