Did you know: The GW-S5600U is the lightest adult G-Shock ever made. However, by replacing the carbon strap with a standard Casio GW-5000 strap you can further reduce the weight by 15%? :
FS: New In Box Casio G-Shock GWM-5610BB Atomic Solar $60 Shipped USA Only | WatchCharts
Casio G-Shock Gw-m5610bc and Gw-m5610nv customs - myWatchMart
The updated G-Shock Square GW-M5610U with module 3495