BEAST 4-Piece Carbide Porcelain Drill Bit Set for super fast drilling on the hardest surfaces. Each set a 1/8", 3/16", 1/4" and 5/16" drill bit. For use on PORCELAIN, MARBLE, GLASS, CERAMIC, MIRRORS, TILE, QUARTZ and GRANITE. Carbide tip specially formulated and designed for quicker drilling and greater durability. For use, installation and saftely recommendations, see package directions.