According to the official Casio Europe online shop (casio-shop.eu), the G-Shock GA-2100-1A1ER is the top-selling product in 2021. This is not altogether surprising, as massive demand and a worldwide shortage followed the watch’s launch in 2019.
The GA-2100-1A1ER is currently available in certain European countries at de.casio-shop.eu (destination country is selectable). It is also available in the U.K. at g-shock.co.uk and sporadically in the U.S. at gshock.com.
In August, G-Shock is launching the GM-2100 and GM-S2100 series featuring a stainless steel bezel, starting in Japan. Like many of the GA-2100 models, some of these GM-2100 models are likely to sell out in some areas. Pre-orders for the silver, blue, and green models sold out quickly at the Casio Japan online shop and other Japanese retailers.