Aiskaer 70mm High-grade Diamond Hole Saw Diamond Tipped Tile Ceramic Glass Hole Saw Drill Bit This diamond coated core drill bit removes a complete circle from glass, tiles, marble, granite, cer Easy to use, high quality,good performance, long life - Excellent for making clean and accurate hole Always use lubrication (water ), otherwise the diamond core drill will burn - Start your hole diagon Start your hole diagonally, make a round trace and then hold drill straight. size:70mm