Smartphone Link Functions (about 300 World Time cities, alarm, timer, hand alignment correction, home city time swapping, phone finder) Battery level indicator New layer guard structure 200-meter water resistance From G-SHOCK, the watch that always strives for toughness, the first G-STEEL lineup models to offer chronograph performance in analog format. Thought all the dials of these models are analog, they still boast G-SHOCK level shock resistance. The dial at 9 o'clock has a multi-functional rotating disk that is cut to resemble the thick blades of a jet engine. Rotation of the blades reveals red coloring behind the disk, and this change in color is used to indicate the battery level and the alarm on/off setting. The blades also rotate in the Timekeeping and Stopwatch modes to with the passage of time. A new layer guard structure houses resin cushioning parts inside the case, for a more elegant design and a better fit to the wrist. High density mounting technology makes it possible to create a module that is smaller and thinner, which also contributes to a better fit. These watches are equipped with Bluetooth that lets them connect with a smartphone at the press of a button, and acquire time information from an internet time server. The result is accurate timekeeping no matter where in the world you happen to be. Other functions include Tough Solar in combination with CASIO original power saving technology for a stable supply of power, highbrightness LED light illumination, and dual dial World Time. The GST-B100D comes with a simple stainless steel band, while the GST-B100 features a solid case and urethane band.