Combination whetstone Shun KAI. Grain: 1000/4000. Package: 21,0 x 7,0 x 3,0 cm. Before use, the whetstone should be completely soaked in water for about 10-20 minutes. Please make sure that a light film of water is always visible on the surface of the stone during grinding. By doing this you ensure the knife edge is sufficiently cooled.