Excellent for easily sharpening kitchen knives PRESTO and other knives with smooth cutting edge. Made of resistant plastic, sharpening disks of hardened ceramics. Place the knife sharpener on a flat surface and hold firmly. Insert the knife with the blade facing the sharpener and stroke several times towards yourself to sharpen it. Wipe with a moistened dishcloth after use. Do not wash in dishwasher. 3-year warranty.