Suehiro Cerax Soaking Japanese Whetstone Polishing and Sharpening StoneWhetstone size: 206 x 73 x 50mm Soaking type Includes Nagura Stone Can Sharpen stainless steel and carbon steel knives. Cannot sharpen ceramic and titanium knives Soaking type: Before use, the stoneneeds to be soaked in the water for 5 10 minutes. this allows the stone to absorb water which will decrease the heat while sharpening and makes sharpening smoother. Together with the watery sludgeas lubricant,this will result in an overall better sharpening