AccuSharp Tri-Stone sharpening system. 3-stone system: coarse diamond (120 grit), medium aluminum-oxide (180 grit), and fine ceramic (240 grit). Stones are easily rotated and secured into position with no oil or water needed for sharpening. Includes an angle guide to ensure knife or tool is sharpened at the correct angle. Slip resistant, rubber-grip base keeps the unit steady while in use. Can also be mounted for extra stability. Ideal choice for chisels and all straight-edge blades.