I just answered this question on another thread lol. I have used this little diamond steel for many years. I have one in my field dress kit, tackle box, truck, and one in the kitchen. It has a groove for sharpening fish hooks, and one side is flat, so it will fit easily into most any gut hook. The steel itself retracts into the handle and tightens like an exacto blade. Worth every penny of the $10 cost.