Compressor wheel is an essential part of the turbocharger characterizing airflow and turbo efficiency. Its structure and design have come a long way since the first forced induction engines saw the light of day. In the past turbochargers’ manufacturers used only cast impellers, as they were fairly cheap to fabricate and met raised requirements. Billet or "Machined from the solid (MFS)" impellers came into the production when market started demanding lower quantities and non-standard designs. The machining process allows to fabricate smaller volumes without additional production costs. Although billet compressor wheels do not have big performance advantages when used in standard applications, cast impellers are likely to show signs of fatigue after less duty cycles, especially when used in higher RPM and pressure turbochargers.