In order to achieve the optimum sharpening angle please match your knife with the appropriate guide rail according to the width of the blade between the back of the blade and cutting edge. Small size Guide Rail should be used for knives with blade width between 15-mm and 25-mm. Large size Guide Rail should be used for knives with blade width between 27-mm and 43-mm.
Attach appropriate Guide Rail to back of blade, slightly nearer to the tip of the blade than the handle, so that the bottom edge of the Guide Rail is parallel to the blade edge. For safety and convenience - whetstone sharpening is only suitable for European and Japanese knives. Made in Japan, lifetime warranty.