As our smart phones get smarter and smarter one thing that doesn't improve is the battery life. My iPhone won't even last a full day if I'm using it heavily and I can't always get to a place to plug it in. External batteries used to be too expensive for me to justify. This one is not. At the price it is selling for on Amazon right now, it's worth the investment.
I own another external battery which only came with a USB to micro usb cable (basically a cable for charging the battery). The OXA comes with a USB cable with multiple adapters to fit micro USB, 30 pin Apple, and more. The only thing you need to be aware of is even though the documentation says it works with iPhone 5s and the new iPads, while it will charge them, it does NOT come with a lightning connector. You will need to use your own cable. For other devices, the end of the USB cable pops off and you can pop on an adapter for them.
Simple to use
No battery meter
The only drawback to this battery is the fact that it lacks a meter. While I might be able to get multiple charges out of it, I don't know if fully charging my iPhone drains it 50% or more or less. Therefore, I would recommend recharging it after each use. At the original list price, I would expect a battery meter. At the price it's selling for now, I can live without the meter.
OXA 2600mAh SAFE External Battery 18M WTY Premium Samsung Cells Key Chain charger external portable power supply (Check Amp for tablets) for Smartphones and other electronic devices