7 Main Features --- 4.3-inch LCD screen; 16 different types of doorbell chimes; Adjustable volume, brightness, and contrast; IR camera with night vision; Electric lock control function; Hands-free intercom; Auto power off. INTERIOR INTERCOM MONITOR: When someone presses the call button on the outdoor unit, you can see and speak to anyone who comes to your door. You can safely and easily open the door lock from inside your home. EASY INSTALLATION --- Surface mount, easy installation system 4-wire kit includes rain cover, connection terminal, and screw hardware. (Note: *1* We suggest testing the doorbell kits with our original cable before installation, and the distance between the units should not be too close during testing, otherwise it will cause noise. *2* Please do not connect the power adapter directly to the outdoor unit or it will be damaged. The power adapter should be connected to the indoor unit.) 4-WIRE VIDEO INTERCOM SYSTEM: 4.3-inch color LCD indoor monitor built with an easy-to-use operating system, slim design, and stylish touch button. Beautiful outdoor doorbell with HD camera, 90-degree wide viewing angle, high definition, night vision, rainproof and vandal-resistant design. The doorbell can be connected to any electronic lock. (Lock not included) About the extension wire: The extension wire is not included in the box, but we will provide a 4-pin connector for you to connect the extension wires. You can use RVV4 (0.5MM 4-core wire) / Cat5 / Cat6 wires to extend the distance between the monitor and the doorbell, allowing you to monitor according to your needs, with a maximum distance of 100-200 meters.