The all-new Diamond Pen is perfect for sharpening small pocket knives, serrated blades, and fish hooks. The retractable 600 grit sharpening rod stores easily within the plastic casing. The 3-sided Diamond Pen gives users the ability to sharpen serrations of various sizes. FEATURES: Retractable 600 grit diamond sharpening rod Lightweight plastic casing with clip Length: 5 inches