Hitachi 729408 1-Inch Diamond Grit Drill Bit (Discontinued by manufacturer) The 1-Inch diamond grit drill bit will drill through glass, marble, class 5 porcelain, granite and slate Outperforms the standard carbide glas and tile bits on the market today, both in speed of drilling and the number of holes that can be drilled per bit These bits feature raised lips with diamond grit particles that are uniquely sintered in place allowing the diamonds to adhere to the bit The Hitachi diamond grit drill bit bodies are constructed of hardened and tempered thin wall alloy steel Comes with a 30-day limited warranty