Sharpening stone. Over time, even the best knife will lose its sharpness. If you choose the right ZWILLING J.A. HENCKELS sharpener for your knives and use it correctly, you will not have any problems. With three different materials for a long-lasting sharpness: Refined steel, ceramic or diamond. The two-sided whetstone for slicing and smoothing and for an Asian edge. TWINSHARP Select the sharpener for safe and easy sharpening.