The Casio G-Shock DWN5600-1, the DWN5600-4, and the DWN5600-9 Nano Ring watches are now officially available at the brand's online store in the US. The ring-sized watch weighs just 6 grams (0.21 ounce) and comes with features like dual time, a 1/100-second stopwatch, shock-resistant structure, an auto calendar (up to 2099), and a pulsing light.