For drilling hard porcelain tiles. Smooth, efficient drilling for a clean finish. Extremely long tool life. Crowns fully interchangeable and must be used in conjunction with arbor (Quote 28294). System must be used with Water Cooling Kit (Quote 39598) to increase drilling efficiency and reduce chance of tile breakage. Specifications: Crowns are fully interchangable and must be used in conjunction with arbor (Quote 28291). System must be used with water cooling kit (Quote 39598) to increase drilling efficency and reduce the chance of breakage.