Norton 85440 Sharpening Stone 4" x 1-3/4" x 5/8""CRYSTOLON" SHARPENING STONE Coarse and fine grit sharp cutting silicon carbide abrasive surfaces for general sharpening (to moderate tolerances) when the speed of sharpening is more important than the fineness of the cutting edges 4" x 1 3 4" x 5 8" For fast removal when edge sharpening Oil filed silicon carbide stone Maintains moderate part tolerance Fast stock removal More resistant to particle build up on stone