The 18mm 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 drill bits are available in a range of sizes. For more information please contact the Direct Tile Warehouse team.