ANSIO 3 Stage Manual System Knife Sharpener with Anti-Slip Rubber Base for Grip (Black and Chrome) This is a 3 stage manual system professional knife sharpener. The non-slip rubber base throughout the body of the sharpener adheres firmly to any flat surface thereby ensuring a non-slip, strong grip while the sharpener is in use. The firm ergonomic handle ensures stable grip to protect your hands while sharpening your knives. the main body is made of durable and solid abs plastic which contributes to the firm grip and in avoiding the formation of cracks. Just place your knife in the appropriate slot with a slight downward pressure and run the blade of the knife from the base to the tip. repeat if needed. quick, easy to use with effective results. please note that this sharpener should not be used with serrated knives or scissors. knife sharpener has 3 stages. ceramic stage for sharpening ceramic knives, coarse stage for sharpening dull metal knives and fine stage for knives which need polishing or fine honing.