Casio G-shock GA-B2100-2AER Bluetooth Solar Power Watch Blue Resin Strap Mens WatchModel Specifications: GA B2100 2AER The 45. 4 mm case of the watch is made of dark blue resin. A dark blue resin strap secures the watch. The combination of digital and analogue displays gives the watch its utilitarian appearance. A toughened mineral crystal encases the display. This model has Bluetooth connectivity and can sync to your smartphone through the Casio Connected app. This Bluetooth connectivity enables functions such as the phone finder.