Ideal for sharpening, deburring and general purpose grinding on most materials. The versatile 3/8 In. (9.5 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 932 Grinding Stone is cylinder shaped; however, Dremel offers a variety of grinding stones with different bit shapes to support virtually every possible grinding application.