4 UNITS: 1 outdoor camera and 4 indoor monitors for a visual intercom doorbell system, for two occupants in a building. Individual monitors without interference with each other. The doorbell can be connected to various 12V electronic locks, such as electric locks, electromagnetic locks, cathode and anode locks, etc. It allows monitoring the screen to unlock the door with one key, and unlock the door at remotely via mobile phone app. With PIR motion detection, our video doorbell accurately detects people near your home, effectively capturing human body contours. Radar detection ensures accurate visitor identification, allowing you to receive instant notifications. In addition, the video doorbell records the motion detection and broadcasts it to the monitor, enhancing your home security. Real-time video call: When someone rings the doorbell, our app immediately sends a call to your phone, allowing you to see and talk to the visitor through the monitor. You won't miss any visitors even