➊HIGH-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. ➋SURFACE 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. ➌UNIQUE 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. ➍WIDE 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. ➎10 pieces concrete drill bit with 8MM (5/16" ) SIZES: 10pieces fine grade high durable 8MM drill bits . It Can be installed in the general electric hand drill, bench drill. The machine drill clamp range is 10mm and above.