Casio G-Shock watches are a unique brand that combines tough materials with masculine designs and solar power. The watches contain a rechargeable battery behind a small solar power panel. The solar power panel converts light into electricity, which recharges the battery. While the watches are designed to last for up to five months between charges, this relies on the watch being charged correctly and regularly.

Tilt the watch toward your face to activate the backlight.

Check the battery level. This will have 6 segments. If all 6 segments are visible, the watch is fully charged. If 4 segments are visible, the watch is half charged; if 2 segments are visible, the battery is low.

Remove the watch from your wrist.

Attach the watch to the curved plastic watch holder from the watch box.

Slot the watch holder back inside the watch box, with the lid off.

Place the watch in direct light. A fluorescent light is preferable, as the sun moves and the watch will only be in direct sunlight for a limited period.

Wait for the required time. This is 18 hours of direct sunlight, 87 hours of direct sunlight through a window, or around 25 hours of direct fluorescent light, depending on the model.