Inside the small black nylon case is an Arkansas Washita honing stone made of Quartz Crystal Novaculite. Designed to keep your blades sharpened on the go, the stone can be used by itself, or with water as a lubricant.Buck Knives has more than 100 years of knife making experience, so it stands to reason they'd know a thing or two about sharpening and honing a blade as well. Lightweight and compact, you can keep this stone with your camping gear or tackle box so it will be right at hand when you need it.