The Norton medium-grit aluminum oxide pocket knife abrasive sharpener is a 240-grit aluminum oxide oilstone, suitable for portable hand sharpening and maintenance of cutting tool edges; it produces durable, smooth-cutting edges, and is preferred for close tolerances. This oilstone has a plastic sleeve-style case for protected carrying. It is commonly used to restore cutting edges on flat-bladed tools, household utensils, scissors, and knives. This aluminum oxide stone must be lubricated with oil before use, to prevent metal from bonding with the abrasive surface of the stone. The stone has a tough fracture- and wear-resistant grit that is more durable than silicon carbide and capable of sharpening to very close tolerances. It is created by grading aluminum oxide to a consistent particle size and blending it with bonding agents. It is then molded and surface-finished. An economical grade of aluminum oxide is used for this stone to accommodate lower costs and lower-usage applications. The 3/8 x 3 x 7/8 inch (H x W x D) dimensions of this oilstone make it suitable for hand use. (H is height, the vertical distance from lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.) It conforms to the American National Standards Institute (ANSI) abrasive grit standard. Sharpening stones, or whetstones, are abrasive surfaces used to sharpen and hone the edges of steel cutting implements, such as chisels, knives, scissors, hand scrapers, and plane blades. Sharpening is the process of creating or re-establishing a cutting edge by grinding away portions of the metal to adjust the angle of the edge and reform the shape. Honing removes small imperfections. Stones can be flat, for working flat edges, or shaped, for edges that are more complex. Sharpening stones are made of natural or synthetic materials that range from softer to harder, and are categorized by the size of their abrasive particles, known as grit. A stone with a coarser grit is used when more metal needs to be removed (e.g., when sharpening a nicked or very dull blade); the stone with the finest grit produces the sharpest edge. Where numbers are assigned to specify grit, they range from coarser grit (low) to finer grit (high). Some sharpening stones are designed for use with a lubricating liquid, some can be used dry, and others can be used either wet or dry. When used with lubricating liquid, a sharpening stone can be called a waterstone or an oilstone, based on the lubricant required. Norton Abrasives manufactures sanding, grinding, and polishing abrasives, and has been located in the United States since 1885. Norton, now a brand of Saint-Gobain, meets ISO 9000 and 14001 certification for quality and environmental management standards.