The Bolide Technology Group BE-VDPC is a video intercom system that lets you see and hear a person calling at your door before you open it. When the door bell is pressed, the image of the caller instantly appears on the high resolution monitor. You can then lift the handset to hear and speak with that person. You can also hit the door strike button to unlock the door, provided your door is equipped with a door strike mechanism. The camera part of this system is equipped with IR illumination and will provide you a clear picture of your caller even in the dark. There's also an alarm button on the main unit which you can activate to deter an unwanted visitor.