Casio G-Shock introduced some of its most tech-savy releases to date with the debut of Bluetooth technology for its timepieces, the GB-X6900B. Essentially it’s like the DW-6900 but this design incorporates Bluetooth v4.0 and boasts a new 2.0 engine that allows for two-way communication between the watch and your smartphone via a free app. Thus, your watch can be used for everything from operating music playback and setting alarms to receiving email and call notifications.