This is an accessory monitor to the HFX-700M Door Bell Camera kit. This monitor measures 3.5 inches and is a full LCD display for crisp images. Technically meant to receive the images captured by the Door Bell Camera, you can also establish a monitor-to-monitor connection (4 monitors total) for use as a video-intercom system, as it is equipped with a reliable 2-way communication system that includes a mic and speaker.