A few strokes in the diamond grooves will sharpen any hook...sharp hooks catch more fish! Hone hooks and fish fillet knives with the Angler Mini-Sharp® Diamond Fishhook Sharpener - the Diamond Whetstone™ that travels with you. Easy to use and convenient to carry or store in your tackle box. Flip open lid/handle. Swivel ring for key chain. 5-1/2" (140 mm) when open.