A good sharpener is a must for any knife owner and these by DMT (Diamond Machining Technology) offer a quality diamond sharpening tool at a reasonable price. As they are made from diamond, the toughest material around, these sharpening stones are guaranteed to last. They will hone the hardest material with less time and effort than conventional stones. Interrupted pattern increases cutting action while clearing material from the diamond surface. It reqiures only water as a lubricant and is virtually indestructible.