Efficient Universal Drilling (5PCS)No need to add water, you can drill to the bottom in one click. Universal various materials, efficient drilling. Main Features HIGH QUALITY MATERIALS: It is made of high quality YG6X alloy as raw material. The process of oxynitriding of the cutter head strengthen the drill hardness. SURFACE ELECTROPHORETIC PAINT PROCESS: Full grinding and anti rust treatment, clean and sharp without burrs UNIQUE CROSS ANGLE DESIGN: Small incision resistancefeature