The Compact 21 system is the new Riber baseline MBE system. This versatile reactor is a flexible and affordable system with features carefully designed to meet the highest specifications for the research of all compound semiconductor materials. Based on Riber's field-proven "Vertical Reactor" technology, Compact 21 is a 2"/3" integrated system, providing, within a small footprint, all the necessary MBE facilities and state-of-the-art characterization capabilities. Furthermore, because of its ergonomic and modular design, operation and routine maintenance are both extremely easy. Depending on the application (process and substrate size) two epitaxy chamber configurations are available: seven source ports (Compact 21S) or ten source ports (Compact 21T). Eleven source ports available upon request. Introduction of samples is implemented by the use of: (1) loadlock chambers (R&D systems), or (2) modular transfer modules (Modutrac™), enabling the addition of chambers for specific treatments (metallization, sampling, analysis, outgassing, etc.).