The 12mm drill bit is vacuum brazed unlike other brands of drill bits which are electroplated or coated with diamonds as a cheaper alternative. By manufacturing this way our drill bits will last longer which saves you time & money. They are designed to fit into a normal drill for use in drilling holes in marble, granite, porcelain, glass, ceramic and cement. These 12mm drill bits are also available in other sizes. For more information please contact the Direct Tile Warehouse team.