Ideal for sharpening, deburring and general purpose grinding on most materials. The versatile 1 In. (25.4 mm) diameter Aluminum Oxide Grinding Stone works well for extended general purpose grinding on metals, sharpening tools, castings, welded joints, rivets and rust removal. The 8215 Grinding Stone is disc shaped; however, Dremel offers a variety of grinding stones with different bit shapes to support virtually every possible grinding application.