The most iconic Citizen creation is the Eco-Drive watches.  Eco-Drive is a model range of watches powered primarily by either natural or artificial light. The Eco-Drive system eliminates the need and cost of battery replacement as well as battery disposal. Most Eco-Drive type watches are equipped with a special titanium lithium ion secondary battery charged by an amorphous silicon photocell located behind the dial. Light passes through the crystal and dial before reaching the photocell.