This model is distinguished by its very small size (it is roughly the diameter of a coin of 50 cents, for a length of ten centimeters), its metal body seems solid, and the adapter that is provided . It has a side of a male USB port (to plug in the battery output), and the other 3 connectors: one for iPhone (versions 3-6), a Samsung (type Galaxy Tab ) and mini USB which corresponds to more and more devices (and that's good). I could not test the USB mini with my Acer Liquid Z5 phone.
Charging is done by connecting the battery to a computer USB port or USB / AC adapter (not supplied). LED changes from red to blue to indicate that the battery is charged.
Then the cable is reversed to connect the device to load.
Battery life is not great, but enough to tide one time before having to move to another refill. On my phone, for example, the battery allows me to hand over about 2/3 of its maximum load capacity, in about 1 hour charge.
The main weak point for me is the lack of remaining power indicator: one can know when the battery is empty and no longer supported.
Apart from that, it's a good external battery, compact, robust, easy to use.
