1/4-inch Diamond Core bit with water feed * Drill through porcelain, marble, slate, and glass * Water feed needed to help keep the material and the bits cool during drilling * Drill up to 30-35 holes per bit depending on the material * Can be used with any cordless drill for flexibility and convenience * 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 1/4-inches in diameter * Requires water lubrication during use