EdgeKeeper Chef Knife, 6-Inch, Black Style Name:6-Inch Chef Knife is the #1 selling cutlery brand in the U.S. (Source: The NPD Group, Inc./Retail Tracking Service. 52 weeks ending March 2016). EdgeKeeper Knives feature a sheath with innovated technology that is designed to automatically sharpen the blade with each use. The EdgeKeeper protective sheath contains a built-in mechanism that hones the blade before and after each use, maintaining a blade’s razor-sharp edge. The blade is made from high-carbon steel that lends strength, sharpness, and durability. Knives are not dishwasher safe. Hand-wash with warm water and a mild detergent; rinse and dry immediately..