The 1/2-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