Cyrex Networks EX-750D for homes or businesses that require additional doorbells for multiple entrances, the EX-750D is the perfect solution. This rugged metal, weather proof doorbell can operate in just about any climate. The unit is equipped with a Day and Night chipset operates in color during daytime and automatically switches to B/W in low lighting conditions. A built-in PIR infrared provides supplemental lighting for night viewing from any monitor. The EX-750D requires only 2 wires, which transmits the audio, video and power, so users can safely see and hear the visitor.