Regular use of the Nagura stone ensures that your finer grit stones retain their awesomeness. A stone sharpens because microscopic peaks and valleys of coarse material work to remove steel. Thereby crafting an edge on knives. As a result of sharpening, the stone’s valleys are filled with bits of steel and stone. This reduces the sharpening stone’s abrasiveness and makes it difficult for it to maintain performance. The Nagura stone gently cleans those valleys without removing much material from the sharpening stone. A Nagura stone makes sharpening easier and extends the life of your sharpening stones.