G Shock GMB2100AD 2AD Full Metal Bluetooth brand@Calvin Klein The leather band is versatile The leather band is versatile and a plain black colour that can be paired with a variety of different outfits This range of Casio watches are unique as they link with the GPS of a smartphone for a more accurate calibration of distance measurements that can assist daily health management and running endurance battery operating time: *7 months on rechargeable battery (operation period with normal use without exposure to light after charge) *18 months on rechargeable battery (operation period when stored in total darkness with the power save function on after full charge) Accuracy: ±15 seconds per month (with no mobile link function) Hand shift feature (Hands move out of the way to provide an unobstructed view of digital display contents There is a fine resin component that has been installed in between the bezel and case