Material This drill bit set is made of alloy as raw material. The oxy-nitriding treatment of the bits strengthens the hardness of the drill bit. [Electrophoretic surface painting process] The drill bit set is fully stainless steel ground, clean and burr-free. The drill bits are more wear resistant and durable. Fully automatic polishing, polishing is fully automated, each one is unique. [Unique cross-angle design] Low cutting resistance, stable drilling function, no overrun at high speed. Neat and smooth opening, no broken edge, no wobbling phenomenon, easy to pull off. [5 different sizes] Suitable for your different needs. Can be mounted on a general hand drill or table drill. The clamping range of the machine drill is 10mm and above. [Versatile] Professional glass and tile drill bits provide smooth and precise drilling on tiles, marble, thin iron plates, mirrors and glass. Remember to add water or coolant when drilling. Material: Tungsten Carbide Product size 3*70/4*70/5*76/6*77/7*80MM Scope of delivery: Universal drilling tools (5 pieces) Note: Due to differences in lighting and screen settings, the colour of the item may differ slightly from the picture. Please allow for slight variations in size due to differences in manual measurements. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.