Glass Drill BitThese diamond drill bits are made of industrial grade carbon steel with nickel-plated coated body to resist corrosion. Fine workmanship and super wear-resistant, sharpHigh Quality DrillEach hole is treated with smooth and accurate surface treatment,and the top oh the hole is thickened to achieve excellent cutting strengthTile Hole Saw 15 Sizes 6/ 8/ 10/ 12/ 14/ 16/ 18/ 20/ 22/ 25/ 26/ 28/ 30/ 40/ 50 mmto meet various demandsWide UsageUsed on Drill Glass,Wood,Tile Bottles,Blocks Jars, Ceramic,Slate Mable, Granite Light Stone, and other hard surfacesAttentionPlease keep adding water when the diamond drill bits are working on the glass or ceramics.low drill pressure and increased use of water lubrication will extend drill bit life.