The Flexcut Hook Hone is used to sharpen the INSIDE edge of your hook knife. This ingenious sharpening tool uses fine abrasive paper to hone the knife’s bevel, removing nicks and scratches from the cutting edge. It works equally well on single and double edge hook knives. The Flexcut Hook Hone is a tad under 21mm diameter so can sharpen any hook or curved knife blade with an internal radius of 11mm or larger. The Hook Hone takes a 230mm long strip of abrasive paper. Attaching the abrasive is simple using the dowel rod and rubber O-rings provided. The Hook Hone includes 400 and 600-grit abrasive paper and full instructions. We recommend using wet and dry silicon carbide abrasive; no coarser than 400 grit and as fine as you like to achieve a truly sharp edge. Strop after sharpening to remove any minute burrs. A sharp edge makes carving all the more enjoyable.-bg