Smith's 4 inches Diamond Sharpening Stone features a patented interrupted diamond surface, which improves the sharpening process by trapping and holding metal filings removed from the edge, keeping the surface clean and effective. This sharpener includes a micro-tool sharpening pad for sharpening knife tips and small cutting tools, a straight-line groove for fishhooks and pointed objects and a cover that doubles as a base when not in use. Perfect for sharpening hard steel blades, it's especially effective on small to medium hunting knives, tactical knives and everyday pocket knives.