Citizen Chandler Chronograph Eco-Drive AT0205-01E 100M Men's Watch Driven by the Citizen Caliber H500, Eco-Drive movement; what the Chandler needs is light to run accurately over months. Not just bright light; any intensity of light would do. The Eco Drive, once fully powered up, keeps running for months at a stretch without further exposure to light and is a relief to abrupt battery run downs or ritual winding.
