The Walkeer could be powered by a little battery box, as well as USB powered. Pls see it in the attached pictures.

Walkeer is designed as audio solution for iPod, mp3, CD player, laptop,etc.

The detailed tech info as the following,

Dimensions: (Width)150mm*(Hight)120mm

Thickness: 6mm(min);20mm(max)

Total Weight: 170grams (80g per speaker)

Output: 1.2W+1.2W

Max handling power:5W+5W

Frequency Response: 150Hz---20KHz

Sentivity:83dB/1W/0.5m

Max Sound Pressure Level: 90dB