ProFit 0903 1005 Diamond Dry Core Drill with 5/16-Inch Hex, 13/64-Inch, Yellow Cut through Tiles, Marble, Granite and Concrete No water needed because of the cooling wax in the center of all pilot drills. No water = Less mess Start the hole with the pilot drill to keep it perfectly centered and to not risk skidding across the surface. Plug Ejection Feature