Lovingmei LOT 15 Pcs SET Diamond Hole Saw Drill Bit Set 6mm - 50mm Granite Glass Tile - Tools 15 Piece Diamond Dust Hole SAW Drill BIT for Ceramic Tile Marble Rock Porcelain Can be used with a standard electric drill(Excluding in this item) Excellent for making clean and accurate hole on glass , tile and marble Always use lubrication (water), otherwise the diamond core drill will burn Start your hole diagonally, make a round trace and then hold drill straight 6,8,10,12,14,16,18,20,22,25,26,28,30,40,50mm