The DEWALT Glass and Tile Drill Bits allow for easy and accurate positioning of hole and reduced risk of walking. Water greatly improves drill bit life and drilling speed. The central core created during drilling stops drill wandering, and the core can be removed easily through the core ejection slot. For drilling holes in glass, slate, granite and tiles including porcelain tiles up to grade 5. The DEWALT DEWDT6045QZ tile bit set + water delivery system includes a mixed pack diamond tile drill. Sizes: 5, 6, 7, 8 & 10mm.