Drilax&reg; 2-7/8" Diamond Coated Drill Bit Hole Circular Saw (Smaller Than 3 ") Ceramic, Porcelain Tiles, Glass, Marble, Granite, Quartz - Shower Wet Drilling Tool 2 7/8 Inches in Drilax010075 Wet Cutting Diamond Drilling Holesaw Tool 2 7/8" - Slightly Smaller Than 3 inches This is a very rare size. Save %80 over stores. There is no need for a center pilot drill. These tools do not have center pilot drills. Do NOT run dry. Diamond Coated Tools will work best if you use water to keep the tools cool. Shank round and size is 3/8" - Use with standard electric or battery drillers.