[Material] The drill bit set uses alloy as raw material. The nitric oxidation process of the drill bit improves the hardness of the drill bit. [Surface electrophoretic spraying process] The drilling unit is fully rust-proof and polished, clean and sharp without burrs. The drill bit is more wear-resistant and durable. Fully automatic polishing and buffing Fully automatic, each piece is unique. Unique cross angle designLow cutting resistance, stable drilling, fast speed and no upper limit. The opening is neat and smooth, without broken edges, no shaking and easy to peel off. 5 different sizes Suitable for your different needs. It can be installed on general electric hand drills and bench drills. The clamping range of the drill is 10mm and above. Widely UsedProfessional glass and tile drill bit for smooth and precise drilling on tiles, marble, thin iron plates, mirrors and glass. Don't forget to add water or drilling coolant. Specifications: Material: Carbide Product weight: 125G Product size: 3*70/4*70/5*76/6*77/7*80MM Package includes: Universal Drill Tool (5pcs)*1 Note: Due to manual measurement, the size may have an error of 2 cm/1 inch; Due to different displays and angles, the color and size may be slightly different, thank you for your understanding! Welcome to your purchase! We look forward to showing you your shopping experience.