Cyrex Networks EX-750H the convenience of answering the door in any part of the house, then the EX-750H color expansion monitor is an important addition to your system. You can enjoy the convenience of installing up to 7 expansion monitors. As the doorbell is activated, the video is sent to every monitor. From there, users can safely view and answer directly from the any monitor. Furthermore, the monitors function as an intercom so you can broadcast and communicate with other monitors. With its advances features, the monitors operate in color during daytime and automatically switches to B/W in low lighting conditions.