This Chroma Whetstone 1000/3500 is a great combination sharpening stone which will help you keep your Chroma knives in top shape. The 1000 side is medium grit and the 3500 side is a polishing grit. This stone is made of man-made materials in Japan. When sharpening your Chroma knife it is important to maintain the 15 degree edge. Please note this is a water stone and not an oil stone.