This is a seriously small portable phone charger and it was primarily designed for emergency use.

it is small enough for you to carry it around wherever you go, doesn't depend on your remembering to charge it, and it relies on something readily available everywhere: househould AA batteries.                                                                                             Happy trip just by two battery to solve your phone have no power! In the case of  your phone and power bank have no electricity, just need go to any store or shops to buy two 5# AA battery then can charging your phone. It is not a necessity, but must be emergency goods, when your need it, it must be very important goods!!!