DMT Diafold® serrated knife sharpener.Extra-Fine diamond (9 micron / 1200 mesh) to polish and refine a razor edge after sharpening with a coarser diamond. One tool for many tasks an excellent value for home, shop and recreational use. Sharpens in a fraction of the time required by conventional stones. Convenient size: 9 1/2" open. 5" closed. Size of blade: 1/4" to 1/16" taper (6.4mm to 1.6mm). Portable, lightweight with convenient fold & go handles, which enclose and protects the Diafold Diamond Serrated Knife Sharpener when not in use. Extra-Fine diamond to polish and refine an edge. Sharpens knives faster than conventional stones with DMT's monocrystalline diamond surface. No oil is needed-sharpen dry or with water. Durable construction will provide years of consistent performance and reliable service. Made in USA.