An Aqara Hub is required. Smart sensor for every door and window. Install the Aqara Door and Window Sensor on your door or window at home to always know whether they are open or closed. Do you often forget to close your doors or windows? Simply use your phone to find out. Smart control in the Apple Home app. Compatible with other HomeKit-enabled accessories in the Apple Home app to make your life easier. The Aqara Hub is necessary for this product to work with HomeKit technology. Aqara home automation. Together with other Aqara smart accessories, you can create various scenes. Even if the Wi-Fi connection is unstable or disconnected, the automations connected to this product will function properly as long as the hub is powered. The lights will automatically turn on when you open the door. If you open the door in the evening, the Aqara Door and Window Sensor sends a signal to the Aqara Wall Switch to turn on the light. No matter how late you come home, the lights will automatically turn on. Technologically advanced. The Aqara Door and Window Sensor detects the open and closed state of doors or windows through the distance between the sensor and magnet. It consumes little energy, and a button battery lasts over 2 years.