The 440 manual knife sharpener from Chef's Choice ensures razor sharp edge, every single time! It has 2 stages for sharper and long lasting edges. The sharpener has precision roller guides that control the angle for perfectly sharp edges. The 440 knife sharpener's 100% diamond abrasives ensure fast sharpening of the entire edge, from tip to bolster. The sharpener is designed to be used with 20 degree straight edge knives such as chef's, bread, hunting, fillet, and pocket knives.