The Redi-Edge Multi-Tool Sharpener is designed to sharpen both serrated and straight-edged knives. The Redi-Edge Multi-Tool Knife Sharpeners are produced from military-grade aluminum for extreme durability, long life, and lightweight. Design features include a proprietary corrosion-resistant finish and a Diamond Coated honing rod inserted into the body of the sharpener. The Duromite sharpening elements are harder than any knife blade; and factory pre-set to sharpen most blades at a 40 degree inclusive angle to maintain a 20 degree double cutting edge.