Dremel accessories (84922) silicon carbide grinding stones are designed for grinding, sanding, engraving and sharpening of various tough materials These small cone-shaped grinding stones are effective for use on hard materials such as stone, glass, ceramics, porcelain and non-ferrous metals Made from quality silicon carbide for more hardness and better durability Working diameter 4.8 mm; shank diameter 3.2 mm; recommended maximum speed 25,000 RPM Fits with all Dremel Multi-/Rotary tools or other 3,2mm shank size multi- / rotary tools, Weight: 0.01984160358 pounds, Manufacturer: Dremel