This KAI combination whetstone features two sides with different grits - a coarse side and a fine side. With the coarser 1000 grit, you can level out imperfections and perform the necessary preliminary sharpening. The fine 4000 grit is used for the finest polishing of the edge. The combination sharpening stone should be soaked in water for about 10 minutes before use to achieve the best sharpening results.