Casio Men's G-Shock Master of G Series Gravitymaster GR-B300-8A2JFProduct Highlights The GR B300 GRAVITYMASTER incorporates a shock resistant structure called the "Carbon Core Guard Structure," utilizing the characteristics of carbon material used in aircraft bodies impact resistance, rigidity, and durability. Inspired by next generation aircraft, the seamless bezel design combined with a case made of carbon fiber reinforced resin creates a powerful and distinctive GRAVITYMASTER look. Features like the Flight Log