The Drill Bit Guide/Water Delivery System is the perfect companion for Electroplated Drill Bits when installing bathroom fixtures on marble, granite, ceramic, porcelain and glass tile. The Drill Bit Guide/Water Delivery System will not only prevent wandering drill bits but also supply water to cool the cutting edge to get the highest performance and the longest life from the diamond drill bit. A suction cup creates a vacuum that secures down the guide and drill bit during the application. It then easily moves to the next hole in seconds. Use it with Electroplated Drill Bits ranging from 3/16â through 1-3/8â diameter. It is ideal for drilling 1/4â anchor holes when installing towel bars, soap dishes, shelves, cabinets and shower door frames.