Aluminium-alloyed lightweight steels, also known as UHC steels, have a density about ten percent lower than today's high-performance steel and are correspondingly lighter, with similar strength. UHC stands for Ultra High Carbon. To produce this material, the steel is alloyed with a corresponding proportion of aluminium and 1.8 % carbon and is actually considered impossible or extremely difficult to forge. It takes an enormous amount of experience to develop a process that makes forging this material into a knife blade possible in the first place. But only Heimo Roselli himself knows how this ultra-hard steel with a Rockwell hardness of 62-68 HRC and a tensile strength of approx. 2500 N/mm² becomes flexible and thus usable. He had the special forging technique and heat treatment required for this protected as a process.