Mgtgbao 10Pc 3/16?Green Concrete Drill Bit Set, 5Mm Masonry Drill Bits For ?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 .The drill bit is more wear-resistant and more durable .Fully automated polishing: Polished CNC is fully automated, each one is unified. ?UNIQUE CROSS ANGLE DESIGN :Small incision resistance?feature drilling stably, fast speed, not breaking the border. Opening neat, smooth, no broken edges, no tremor phenomenon, chip easily. ?WIDE USAGE: Professional glass and tile drill bits provide smooth and accurate drilling in ceramic tiles, marble, thin iron plate, mirrors and glass. Remember to add Water or coolant when drilling. ?NEW DESIGN: U-shaped drain groove, spiral handle design, easy to remove chips during work, smoother drilling. 10 pcs drill bit set with 5mm (3/16?) sizes: that is 10 x 5mm (3/16?) fit your different needs.