The key to sharpening any cutting tool is removing the steel at the edge while maintaining a consistent angle between the blade and the stone.Spyderco's Tri-Angle Sharpmaker takes the mystery out of this process and enables anyone to sharpen a knife effectively with just a few minutes practice.Its durable ABS plastic base contains keyed holes that accurately set the stones' sharpening angles at a 30° (15° each side) or 40° (20° each side) for sharpening knives.Simply keep the plane of your knife's blade vertical and draw the edge along each stone to sharpen.It's that simple.For serrated blades, use the rounded edges of the stones and a slightly looser grip to allow the stone to flow into the recesses of each serration.The Sharpmaker system includes two sets of high alumina ceramic stones:a pair of medium-grit (brown) stones for aggressive sharpening and a set of fine (white) stones for professional-grade finishing.A set of aluminum safety rods protects your hands while sharpening and all components snap into the self-contained ABS plastic base and lid for easy storage.Every Sharpmaker comes complete with a detailed instruction book and DVD that guides you step by step through the process of sharpening knives, scissors, awls, and many other tools.