The QEP 5/16 in. Diamond Drill Bit is fast and efficient when cutting through porcelain, ceramic, marble, granite and even concrete. Both professional and do-it-yourself installers can use it. Besides the drill bit, the kit contains a guide sleeve, adhesive pads and a water-cooling system (use wet only) Ideal for cutting 5/16 holes when installing towel bars, soap dishes, shelves, cabinets and shower door frames. Drill guide holds hole saw in place during cutting and drill guide sleeve to hold drill bit in place. Fits standard 1/2 or 3/8 drill chucks.