Twist drill bits lattice design, long series suitable for high performance and precise drilling of deep holes on alloyed and non-alloy steel up to tensile strength <700N/mm2, cast iron, iron, non-ferrous metals, hard plastic. The grinding attachment and the 135° self-centring split point allows quick pre-drilling of the drilling process with a lower sliding force compared to the standard grinding tips. Suitable for use on portable drills.