The Tylt Energi 10K's 10,400mAh rechargeable battery can charge a smartphone like the Nexus 5 about four times before running dry.

Photo by: Josh Miller/CNET

You can also use it charge up to three devices at once -- share the wealth.

Photo by: Josh Miller/CNET

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.

Photo by: Josh Miller/CNET

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.

Photo by: Josh Miller/CNET

Sure, it's just a battery pack. But the matte shell and simple blue band is surprisngly fetching.

Photo by: Josh Miller/CNET

The battery pack weighs just under half a pound -- dense, but not exactly onerous.

Photo by: Josh Miller/CNET

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.

Photo by: Josh Miller/CNET

The Energi 10K is larger than a deck of cards, but still just under an inch thick.

Photo by: Josh Miller/CNET

T-Y-L-T.

Photo by: Josh Miller/CNET

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