Casio G-Shock In The Sky Gravitymaster Mobile Link Analog Digital GR-B200-1A GRB200-1 200M Men's WatchThe GRAVITYMASTER is a separate range of even tougher G-SHOCK-s that we call Master of G; it is built to handle the stress and calculative requirements for combat flight missions. The innards of the watch are protected within a tough and rugged carbon core guard structure that’s high-strength, highly weather-resistant and made from carbon fibers reinforced into the resin Casio uses. The Quad Sensor system gives it a compass, an altitude/barometer; a thermometer and an accelerometer, which together come to use whether you are in a plane or climbing a mountain.