The set of four diamond stones includes Extra Course, Course, Fine and Extra Fine Dia-Sharp diamond stones. This range of stones provides everything need to restore old blades or put the finest edge on your tools. The 8" DMT stones are our most popular diamond sharpening stones. Guaranteed not to hollow or groove, DMT precisely engineered Dia-Sharp® Bench Stone with continuous diamond surface assures consistent, even sharpening every time. The 8-in. length is great for sharpening plane blades. Each stone has non-skid rubber feet with the grit clearly marked on side. Sharpening with diamonds is fast and easy. No messy oils needed sharpen dry or with water. Durable construction will provide years of consistent performance and reliable service. For proper tool maintenance, woodworkers, chefs and other professionals rely on the superior quality and versatility of DMT® products. Made in USA.