The bezels are made of a carbon sheet and carbon fiber reinforced resin. The GST-B400X-1A4 has red dial accents, a black ion plating on the stainless steel case, and a textured black resin band. The GST-B400XD-1A2 has blue dial accents, a silver stainless steel case, and a stainless steel band. Both watches measure 46.6 x 49.6 x 12.9 millimeters, with the GST-B400X-1A4 weighing 74 grams and the GST-B400XD-1A2 weighing 154 grams.
The GST-B400X-1A4 and GST-B400XD-1A2 feature shock resistance, 200-meter water resistance, Tough Solar power, Bluetooth smartphone link, world time, stopwatch, countdown timer, 5 alarms, and dual LED lights with a backlit LCD display. These models also have an adjustable date format (M/D or D/M, six day of week languages).
The GST-B400X-1A4JF and GST-B400XD-1A2JF are September 2021 releases in Japan with a tax-included price of 59,400 yen each. G-Shock U.S. is expected to release the black GSTB400X-1A4 sometime later with a list price of $400.