?Glass Drill Bit?These diamond drill bits are made of industrial grade carbon steel with nickel-plated coated body to resist corrosion. Fine workmanship and super wear-resistant, sharp ?High Quality Drill?Each hole is treated with smooth and accurate surface treatment,and the top oh the hole is thickened to achieve excellent cutting strength ?Tile Hole Saw 15 Sizes? 6/ 8/ 10/ 12/ 14/ 16/ 18/ 20/ 22/ 25/ 26/ 28/ 30/ 40/ 50 mm?to meet various demands ?Wide Usage?Used on Drill Glass,Wood,Tile Bottles,Blocks Jars, Ceramic,Slate Mable, Granite Light Stone, and other hard surfaces ?Attention?Please 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.