SONOFF DW2 WiFi Wireless Door Window Alarm Sensor with Phone Alerts, No Hub Required, Works with Alexa & Google Home, Low-battery Reminder, 2.4GHz WiFi Connectivity

✔【Remote Monitoring & Send Alert Information】Put the sensor on your door or window, Your phone will receive an alert message when your’s door or window is opened or closed. Both the opening and closing status of the door/window are synced on your mobile phone. (NOTE: Only support 2.4Ghz. No built-in siren, but the alert message to your phone.)
✔【Smart Scene Linkage】To crate a smart scene linkage between WiFi devices in your home. For example, The room lights up when the door is open, and the room lights go out when the door is closed.
✔【Low-battery Reminder】Real-time battery level display and low-battery reminder ensure you get clear know how long the sensor can run and when you need to replace batteries.