Vitrex 10 2808 Porcelain Diamond Drillbit 8mm VIT102808 Vitrex porcelain diamond drill bits are ideal for use on ceramic, glass, marble and porcelain tiles, and are designed to prevent chipping and cracking.They are perfect for the installation of towel bars, soap dishes, shelves, cabinets, shower door frames.The VIT102808 Porcelain Diamond Drillbit has a diameter of 8mm. VIT102808