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 resistancefeature 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.7DIFFERENT SIZES Suitable for your different needs.It Can be installed in the general electric hand drill, bench drill. The machine drill clamp range is 10mm and above. SPECIFICATIONS Material: Cemented Carbide Color: As picture show Size: 3*70mm, 4*70mm, 5*76mm, 6*77mm, 8*80mm, 10*83mm, 12*83mm (Approx.) Quantity: 7pcs PACKAGE Includes 7pcs Universal Drilling Tool *Notice* 1. Manual measuring, please allow 0.1~ 0.5cm error,thank you. 2. Due to the difference between different monitors, the picture may not reflect the actual color of.