DEWALT DW5586 1-3/8-Inch Diamond Drill Bit cuts modern hard tile and porcelain better than traditional "spear head" bits. The core ejection slot removes plugs for repetitious holes, while the reverse spiral thread delivers continuous water feed for increased speeds and longer life. The 3/8-inch shank fits most standard drill chucks, and this bit has a diamond welded tip for outstanding durability and life span. Maximum RPM is 1,200 to 2,500.