Naniwa professional series is the highest quality stone from Naniwa.They are very dense/hard, which means less dishing, and more steel cutting and polishing properties.
Care for your whetstone:
-This stone only requires a splash of water to start, and the same during the sharpening process.
-Keep stone flat with a truing stone.
-Keep stone clean with nagura stone.
-Wipe stone clean of excess water, dry at room temperature.
-Store at room temp. Keep away from hot and freezing temperatures.