Package Include-----Totally 11pcs/box drill bits: Diameter 1/4''(6mm),5/16''(8mm),3/8''(10mm),4/5''(20mm),1''(25mm),1-1/4''(32mm),1-3/8''(35mm),1-3/4''(45mm),2''(50mm),2-1/2''(65mm); Total length 65mm; Diamond height 10mm; Triangle Shank; Handle diameter 10mm Application-----Dry/wet drilling for Porcelain Tile Ceramic Granite Marble Masonry Stone, etc Cooling Wax and U-grooves Design-----The inside of 6-10mm drill bits are filled with cooling wax, help heat dissipation and chip evacuation. 4pcs U-grooves above 20mm, good for heat dissipation and debris removal, with higher efficiency and better performance High Performance-----High-quality Diamond Grain and Vacuum Brazing Technology provides much longer working life, fast and smooth drlling, durable and sturdy Recommended Machine-----Triangle Shank drill bits suitable for any Corded Drill, Cordless Drill, Benchtop Drill. Use electric hand drill: Recommended speed not less than 2000RPM; Faster the RPM, longer the drill bit's working life. When use Angle Grinder, please install angle grinder drill chuck