Mini 1000 mAh Battery Extender and Mobile Power Station for iPod; iPhone 1G, 3G with (White) Advanced lithium-ion technology keeps your 3G iPhone working at optimum performance Easy to use, Simply attach directly to iPhone, iPod, iTouch without the use of cables Has Test-button for checking status of battery capacity, meters and visualizes how much power you have left Blue light Flashing on while iPhone is on the charging. Blue light Flashing on while the Battery Extender is on the charging, indicates the charging status