An ultra-thin module encased in carbon fiber makes for a stylish G-STEEL timepiece with the slimmest profile yet. Strong, yet lightweight, the carbon core guard structure absorbs external shocks and retains Bluetooth connectivity and solar power functionality even with smaller components and a thinner module. Measuring just 12.9mm from the back of the case to the top of the bezel, the GST-B400 is over a millimeter thinner than its predecessor.