A new tool steel grade of the high thermal conductivity tool steel family. It has been designed to be the most cost-effective solution for applications benefiting from exceptionally high thermal conductivity while requiring good mechanical properties, including very large cross-section applications – thickness ≥ 1000 mm is possible. It provides significant advantages for plastic injection applications due to its outstanding thermal conductivity (twice as high as conventional tool steels), elongation, very high degrees of polishability, and its great potential for reducing cycle time and improving part quality by eliminating warpage and sink marks.