5/16" Diamond Core Bit * Drill through Porcelain, Marble, Slate and Glass * Water Feed Needed * Drill up to 30-35 Holes * Diamond Grit * Comes with a 30-day limited warranty * Constructed of hardened and tempered thin wall alloy steel * Drill bit drills through glass, marble, class 5 porcelain, granite and slate * Glass and tile bit measures 5/16-inches in diameter * Requires water lubrication during use