Features: Made of fine quality material, low resistance, high hardness, improving work efficiency. The design of triangular shank makes the clamping more tight and does not slip. U-shaped spiral groove is smooth and flat, and the drilling is smoother. Strong toughness and wear resistance, can be installed in electric drills. Provides smooth and accurate drilling in tile, glass, brick wall, wood and so on. Specifications: Material: Alloy Color: As the pictures show Type: 4-10mm 5pcs, 6-12mm 5pcs, 3-12mm 7pcs optional 4-10mm 5pcs cutting diameter: 4mm, 5mm, 6mm, 8mm, 10mm 6-12mm 5pcs cutting diameter: 6mm, 6mm, 8mm, 10mm, 12mm 3-12mm 7pcs cutting diameter: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm Package List: Choice1: 5 x 4-10mm Drill Bit Choice2: 5 x 6-12mm Drill Bit Choice3: 7 x 3-12mm Drill Bit