The gadget is AAA battery powered and there's no power adapter or in-built power pack.

ENGADGET

And both will run for about six hours on a single AAA battery.

FORBES: Ten O'Clock Tech: Panasonic's Music Boxes

It has a rechargeable battery that, when coupled with one AAA battery, lets the device run for 50 hours of uninterrupted play.

FORBES: Tiny In All But Price

The device runs for about 15 hours on a single AAA battery.

FORBES: Magazine Article

Unusually they are powered by a single AAA battery, that you sneak into the slightly bulbous section in the middle of the band.

ENGADGET

The smart pen is powered by one AAA battery, and with the help of the energy-efficient Bluetooth 4.0 technology, will last for months of continuous drawing.

ENGADGET: Ten One ships $80 Pogo Connect, a pressure-sensitive Bluetooth 4.0 stylus for iPad

The Hydra comes in either 1GB or 2GB flavors and features an integrated FM radio, USB 2.0 for both quick data transfer and charging the bundled AAA battery.

ENGADGET: Ultra's Hydra: Ohio's full-featured 2GB MP3 player for just $60

Battery troubles pose the single biggest reason for AAA response calls during the summer, according to AAA. Another common problem is overheated vehicles--especially big rigs towing boats, say, or ATVs.

FORBES: Magazine Article

The Nao also has all of the features of its less advanced counterparts: water resistance, a comfortable and easy-to-adjust strap and a rechargeable Li-ion battery that, in a pinch, can be swapped out easily for two AAA batteries.

WSJ: The Petzl Nao: A Smarter Light | At Play