This iSi Vulkanus Knife Sharpener is the tool that will become the center of all your prep and cooking activities. It's the convenient go-to device for keeping your knives razor sharp. Because of the unique pivoting arms, the Vulkanus sharpener will follow the angle of your knife's edge and maintain that angle indefinitely with less than a minute's work. Electric sharpeners grind metal away and actually change the shape of the blade. The Vulkanus sharpener, with a hardness of HRC 93 on the Rockwell scale, removes just enough material to keep a sharp edge. 4 to 6 pulls is all that is necessary. Not only that, the Vulkanus both sharpens and hones your knives to keep them razor sharp. It even sharpens serrated knives.