The most versatile of the pull-thru knife sharpeners available from Smith's is the Carbide / Ceramic Pull-thru Knife Sharpener. This sharpener uses pre-set carbide blades and crossed ceramic stones to bring your knife's blade to razor sharpness. The triangular shaped ceramic stones can be used on either straight or serrated edges. Like the other pull-thru sharpeners, it has an ergonomically designed, soft grip and non-slip rubber feet for comfort and steadiness when sharpening. This unit works best when trying to sharpen very dull or damaged blades to razor sharpness, but can also be used to maintain the edge on already sharp knives.