Above all, you can use the watch without a mobile phone, for example to track a running workout or a cycling tour. My best experience has been with Ghostracer, where you can upload the training directly to Runkeeper or transfer the gpx file to another fitness portal. Of course, you can only communicate directly with your mobile phone via Bluetooth or WLAN (messages, for example). The watch also works with an iPhone, tested by my son.

To set the date and time, you need a mobile phone or tablet with Android 4.3 and Bluetooth. On the Android device (which does not necessarily have to be from Sony), you need the app "Android Wear" for this - secure connection between watch and mobile phone/tablet with Bluetooth. There are also other apps: If you want to design the display yourself, you can use "Intellicom Watch-Faces", for example. - To save power, you can switch to flight mode so that Bluetooth, GPS and WLAN are switched off.