High-performance CCD camera (CMOS camera optional), with infrared illumination to easily identify      visitor even at 0.1Lux.    Noctilucent keyboard. Individual unlocking control circuit ensures the reliable unlocking.    Up to 4 monitors can be connected with the door station. Colorful or Black / White system is      selectable.    Various kinds of general color or Black / White displaying could be selected for monitors.    Dual conversation between door station and monitor.    Power supplier: adapter plug-in.