: A primary "upgrade" was the significantly improved battery, which lasted several days, beating out the Apple Watch Series 4 at the time.

: Part of the Gravitymaster series, this watch featured "tough solar" power and Bluetooth connectivity for aviation-focused upgrades. G-Shock GR-8900-1ER

: Samsung improved its software to automatically track and monitor favorite health and fitness activities more accurately than previous models.

If you are referring to a different "GR" model, these were also notable in or around 2018: Casio G-Shock GR-B100 (2018)

: A solar-powered model known for its and a suspended mechanism for ultimate shock resistance. Christopher Ward C60 Trident (2018)