CNBTR 45mm 1-3/4" Diamond Coated Drill Bit Hole Saw For Glass Marble Opening Tools Small incision resistance, chip easily, improved drilling speed, ease of decoration after opening high quality. good performance, long life This diamond coated core drill bit help to make a complete circle from glass, tiles, marble, granite, cer Easy to use:Start your hole diagonally, make a round trace and then hold drill straight.