Powerbanks have very long lasting life.10000 mAH is a sufficient capacity for power banks. It can charge most smartphones upto two or three times. There are two ports in the powerbanks- one port is used for charging mobile or tablet and the other port is used for charging the powerbank. Powerbanks can be easily carried anywhere. But if it used for long time it becomes hot so it must be used for sufficient time period. So this is the best product at this price. I am also using it this gives best results