To obtain an effective sharpening of the Japanese knives, without damaging the knife, it is necessary to have the correct combination of stones, with different grains. Each knife may need a different grain to be reground: different grain if you have to remove irregularities, if it is a pre-sharpening, a finish or if you have to polish the wire, to make the cut more slippery. The coarse grain 600 to reconstruct the wire or eliminate irregularities or bevels, the 1500 grit to remove the microbanks that were formed with the first sharpening. the passage to the grains 2000 - 3000 - 5000 and 8000 to sharpen and polish the cut, creating a slippery thread par excellence. All the stones must be immersed in water for 5-10 minutes before use. The blades go in both directions at an angle of 15-20 ° and the included guides allow you to keep the right inclination angle. Size of the 3 stones 18 x 6 x 3 cm. The stones have a combination: 600 and 1500 2000 and 5000 3000 and 8000 All stones have a rubber base included. Excellent gift idea for those who want to better sharpen their knives.