Diameter 18mm TDXCEL Range Professional Ultra Hard Material Drill Bits This range of drill bits offer unrivalled performance and cost per cut when drilling the hardest of man-made and natural decorative materials. No water is required. The M14 connection allows use on an angle grinder and with the seperately purchased adaptor (Part Number: TDXM14HEXSET) these drills can be used in a Mains powered drill with a three jaw chuck. (For use on angle grinders & mains powered drills) Applications: Porcelain, Granite & Ceramic Tile.