Have you ever been in one of those situations where you didn't have the luxury to use your phone so the battery won't die? We bet you have. That is why you MUST always have back-up for any emergency.
With a 12000mAh capacity it can charge your phone more than 5 times over so you can use your devices endlessly with no worries.
The LED display shows the percentage of the battery available so you know when it needs to be charged up.