✽【NOTES】An Aqara Hub is required and sold separately. Requires a secured 2. 4 gigahertz WiFi network connection. The Aqara M2 or M1S Hub can connect up to 128 devices(*use of a repeater such as the Aqara Smart Plug or Aqara Smart Wall Switch(With Neutral) is required)..【UNAUTHORIZED ENTRY DETECTION】Whenever the door/window opens unexpectedly, the Aqara Door and Window Sensor will send an alert notification to your phone and activate the local alarm on the Aqara Hub..【HOME AUTOMATION】The Aqara Door and Window Sensor can control other Aqara connected devices as the status of the door or window changes..【22MM WIDE GAP ALLOWED】The Aqara Door and Window Sensor works with most types of doors, windows, and other fixtures with similar mechanism, such as drawers, cabinets, and more..【VOICE CONTROL】Compatible with Apple Home Kit, Alexa for a hands-free experience. In addition, If you have any questions, please feel free to contact us.