A watch like this says you mean business. Crafted in stainless steel with a black dial, luminous hands, date indicator and sophisticated black leather strap. This watch is powered not by an ordinary battery, but by converting photo energy to electrical energy. Before using, expose to light and make sure the watch is sufficiently charged. Time Required for Charging. A secondary battery is used in this watch to store electrical energy. This secondary battery is a clean energy battery which does not use any toxic substances such as mercury. Once fully charged, the watch will continue to run for about 6 months without further charging. To use this watch comfortably, make sure that the watch is always recharged before it stops. There is no risk of overcharging this watch. (Overcharge Prevention Function is provided) We recommend that you recharge the watch everyday.