These are carbide replacement blades for the Smith's Adjustable Angle Pull-Thru Knife Sharpener (item # 50264). Tungsten Carbide Blades put a quick sharp edge on dull or damaged knives. These carbide blades are precision ground to provide a smoother, more consistent sharp cutting edge on your knife blade. They also sharpen your blade quicker than standard carbide blades. These blades come two per set. One for each side of the slot. These blades are replaceable only.