This is the CASIO smartwatch, DW-H5600-2JR. It's a gray G-SHOCK watch with heart rate measurement and smartphone link capabilities, and it supports solar charging. With a full charge, it can last for 5-6 days. Even if the battery runs out, the watch function can still be used thanks to solar charging – this was the most pleasing feature for me. I originally bought a G-SQUAD, but the battery only lasted for a day, making it impractical. I purchased this model instead. The compact size and the battery life of almost a week make it a very user-friendly model, I think. It connects to your smartphone via Bluetooth, allowing you to check messages and LINE notifications on your watch. I purchased this new at Bic Camera Shinjuku store in July 2023. I wore it 2-3 times a month during my commute. The photos are from August 2025. The box, charging cable, instruction manual, and receipt are all kept, and I will ship them together. - Model: DW-H5600-2JR - Functions: Heart rate measurement, smartphone link - Water resistance: WR20BAR - Charging system: Solar charging, USB charging - Color: Gray Thank you for looking.