1 Instant notification: When doors and windows are opened or closed, instant notifications will be pushed to your mobile phone immediately. Let you know the situation at all times. 2 Alarm reminder: Whenever the sensor is triggered to open/close, it will send an alarm to remind you that someone has opened your door or window. 3 Alarm record: You can view the open/close record and battery level in the app, so you dont have to worry about missing any important moments. 4 Low voltage reminder: When the battery power is low, it will automatically remind you to replace the battery, so there is no need to worry about the battery running out.(2 AAA batteries not included) 55: Family sharing: On the APP home management page, share the sensors you added with your family, so that they can also monitor the status of doors and windows.