From G-Central. I like that Casio is coming out with more models with standard lugs that can accept standard straps without using adapters.
Quick Release Replacement Bands for G-Shock GA-2000
G-Shock, News, Shopping
G-Shock GA-2000 owners who are worried that they might be at the mercy of Casio when it comes to replacement bands can rest assured that “quick release” straps from other manufacturers will also fit the GA-2000.
This video review from TimeToGo Travel And Timepieces (at 5:25) shows the GA-2000 swapping straps with a Barton quick release silicone watch band. The proper band size to use is a 24 millimeter width as seen on an aftermarket band in this forum review and mentioned in the video review.