Turn your Dremel rotary tool into a simple-to-use rotary grinder with the Aluminum Oxide Grinding Stone. Ideal for sharpening, deburring and grinding on most materials. The versatile 7/16 In. (11.1 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 911 Grinding Stone is oval shaped; however, Dremel offers a variety of grinding stones with different bit shapes to support virtually every possible grinding application.