As the modern mobile phones, unfortunately, suffer because the battery life is getting worse, such an external battery charger is recommended. By USB ports can be a variety of devices to charge (in my case, private and business phone / iPad) and it is for me to become a unverzichtlichen companion. The only drawback is the size, but this is when you look at the high mAh value clear (!) With this device can be an iPad once charging If you primarily looking for a portable emergency solution for a normal mobile phone, you can be much smaller and lighter models grab. With this, however, you are ready but already for several days.