HIGH-QUALITY MATERIALS: It is made of high quality Cemented carbide 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.5 DIFFERENT SIZES: Suitable for your different needs.It Can be installed in the general electric hand drill, bench drill. The actual color is slightly different, 3+4+5+6+8mm is 1 setMaterial:Cemented carbidecolour:Photo ColorPackage Contents:5 * Universal Drilling ToolOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.