VDOMUS Professional Chef and Kitchen Knives Sharpener,2 Stage and Scissors Knife Sharpening System, Black Dual stage knife sharpener keeps your kitchen knives a professional sharpening right at home Perfect for all knives and scissors with a fine edge, sharpens your knives and scissors quickly, easily and accurately Designed for Safety with Non-slip Feet Avoid too much force.pull back in single direction (Note:don't pushing and pulling back and forth ).normally need 3-5 times only