LEMFO Bluetooth Leather Smart Watch with Camera IPS Screen 360mAh Battery Waterproof for iOS iPhone Android Smartphone (Black) You need to install the app for sync function in your iphone or andriod smartphone before you use the watch. If you want to receive the message or the app notification on the smart watch, you will need to turn on the function on the app. You can find the address to download the app in the user manual. The smart watch connects with the phone through bluetooth. If the watch is out of range, the bluetooth will be disconnect. In general, it will be connected in 10 meters.