Dewalt Diamond Tile Bits provide a quick, clean way to precisely drill through the densest, most-abrasive tiles, including glazed ceramic and rock-hard porcelain (both solid-body and glazed). The bits feature an ultra-durable welded-diamond tip, which easily outperforms and outlasts conventional masonry bits. Reverse spiral threads permit continuous water cooling, so you can run the bits at higher speeds without fear of overheating. There?s even a core-ejection slot that removes a plug of waste material, which is ideal for repetitive hole-boring jobs.