Next Gen Core BitHigh Speed Diamond Core bit for granite, marble, quartzite, quarts, engineered stone, concrete counter tops, and all natural stone. With diamonds on the barrel to reduce drag, heat, and friction, along with high diamond content segments, dry diamond core bits can drill holes in 3cm granite in less than 30 seconds. The High Speed Diamond Core Bits are the best dry diamond core bit for granite and engineered stone counter top faucet hole drilling. They