4 / 6 / 8 / 10 / 12 / 14 / 16 / 18 / 20 / 22 / 24 / 26 / 28 / 30mm Drill bit for precise drilling of steels and plastics thanks to its self-centring sharpening. Tri-flat shank enables maximum torque transmission and prevents the rotation of the bit in the chuck. Specially adapted for through-holes.