SONOFF SNZB-04 - ZigBee Wireless Door/Window Sensor Sync Status & History Records Check Sync the opening & closing status of door/window. With 3-month history records check, help you master your home security clearly. Smart Scenes, Work With WiFi Devices Simply connect the sensor with your devices, turn on/off the lights when you open/close the door. Voice Control & Camera Binding Want to check your door/window close or not? Just ask your Alexa/ Google Assistant instead of opening your phone. You can also add a camera to the sensor to scare the stranger off with your voice. Easy Installation & Low-battery Notification Using 3M adhesive to easily mount the sensor at your ideal locations. Replace the battery in time with a notification when the battery life is 10% remaining. Note Zigbee Bridge required. Keep a distance of less than 80M between SNZB-04 and Zigbee Bridge (open space).