Modelica Standard Library (MSL) is an open source library developed by Modelica Association, which provides lots of models covering many physical fields, such as mechanics, electric, hydraulic, thermal and so on. In principle, users can develop any models to accomplish their product design goals based on MSL. However, in the praxis, users still need to take advantages of other commercial libraries based on proved industrial projects, so that they can build the desired models rapidly and accurately. Furthermore, the commercial libraries also have accumulated a lot of engineering experiences, technologies and expertises and templates to help users to save modeling efforts. SimTek provides independently developed Modelica model libraries by world-wide leading library suppliers.