These subseries come with Bluetooth
G-Shocks with bluetooth can be connected to one of Casios smartphone apps.
Depending on your watch, the app can be used to do things like:
- time syncronisation
- adjust watch setting (eg. time zone, alert, timer, ..)
- syncronise fitness data
- transfer tracks
On some bluetooth models like the GBA-400 you can use you watch, to control the music played on you smartphone.