... calendar 3. 12/24 hour conversion 4. temperature display 5. cell battery inside led clockSelf developed LED electronic products:LED clock comes ... Supply: DC 6V/500MA power supply, external power, built-in button batteries, when power normal travel time.Specifications:The digital clock ... lights up when it is afternoon.5, built-in CR2032 button battery (under normal circumstances, it can work 4 to 5 years ...