IRONCAD makes use of two different "solid kernels" at the same time! Parasolid, from Siemens, and ACIS, from Spatial (Dassault), coexist in IRONCAD to find the best way to build a topologically and geometrically correct 3D model. This makes IRONCAD very good and stable at importing, managing, modifying and exporting 3D models to and from various other 3D CAD file formats.