Bosch 2608900591 HEX-9 HardCeramic Drill Bit 7mm The Bosch 2608900591 has a 7mm diameter and an overall length of 90mm. As wall tiles have become larger and harder, drilling holes in them has become very demanding on a tile drill bit. That s why Bosch has developed the EXPERT HardCeramic Drill Bit, which is capable of dry-drilling hard ceramics and lasts far longer than our benchmark drill bit for tiles. Ideal for drilling holes in bathroom tiles, e.g. to install a shower partition wall; and drilling in roof tiles, without the need for cooling Drills comfortably in tiles up to a hardness of PEI 5. Features: The Bosch EXPERT HEX-9 HardCeramic Drill Bit is designed for drilling ceramics and can drill holes in hard tiles without lubricant or cooling Lasts up to 10x longer than a standard tile drill bit Extremely durable drill bit tip with Bosch Carbide Technology Hex shank for maximum power transfer in standard three-jaw drills and hexagonal drill driver chucks Efficient drilling in hard