Movement
Quartz watches whose battery is recharged by light, which Casio calls Tough Solar. Our two, the GW-5000U and GW-M5610, also set themselves by radio signal using Casio's Multi-Band 6.
2 references we cover.

Casio · G-Shock Square
G-Shockref GW-5000U-1
$240–$320 typical ask
219 on eBay

Casio · G-Shock Square
G-Shockref GW-M5610-1
$140–$230 typical ask
196 on eBay