ML621 lithium button cell is rechargeable, with a 3.0V & 2.5V working voltage, 6mAh, ideal for using on watch, electric toys.. ModelML621Nominal Voltage3.0VStandard Charge/Discharge Current0.05mACycle Life60~100 timesTemperature Range(centigrades)-20~60Weight0.35gApplicationWatch, medical apparatus, thief alarmsetc lithium button cell ML621