The Tylt Energi 10K's 10,400mAh rechargeable battery can charge a smartphone like the Nexus 5 about four times before running dry.
You can also use it charge up to three devices at once -- share the wealth.
A power-hungry iPad will make a serious dent in the Energi 10K's reserves, but it'll offer enough juice to top up several smartphones.
Five blue LEDs give you an approximate idea of how much juice you have left. That said, it can be a little hard to gauge how much juice you've got left.
Sure, it's just a battery pack. But the matte shell and simple blue band is surprisngly fetching.
The battery pack weighs just under half a pound -- dense, but not exactly onerous.
Some battery packs offer built-in charging cables, but those are rarely device agnostic, and can be awkward to use. The USB ports here are nice and accessible.
The Energi 10K is larger than a deck of cards, but still just under an inch thick.