Three indicating light to detect the charging condition of all digital products. Light 1 means it is in testing process. Light 2 means it is in charging process. Only when a USB output voltage, Light 3 will be on. When no voltage output USB port, this indicator is not bright. You can switch the switching positions to choose different modes as you need. You can use this emergency charger to charger mobile phones or other digital products by just placing 5 size or AAA size battery in the universal emergency battery charge warehouse. AC input voltage: 100-240V 50/60HZ. DC input voltage: 1.0-1.6V that is 1.2V (5 size or AAA rechargeable batteries) or 1.5V (5 size or AAA batteries). Universal charger output: DC 4.2V 250-350mA. USB output: 5.5V 200-300mA.