BACKUP POWER in the palm of your hand

BoostBloc series batteries,

$40-$100, www.etoncorp.com

Demand for electronic devices seems to be growing more quickly than the number of outlets available to charge them. Hoping to provide power to those in need, Eton has introduced a series of portable backup batteries, BoostBloc.

The BoostBloc comes in three power options, with lithium-ion batteries that provide an electrical charge measured in ampere-hours. For instance, Eton's most powerful, the BoostBloc 6600, provides 6,600 milliampere-hours, enough to fully charge a smartphone three times.

The charging blocks in the BoostBloc series range in price from $40 to $100. Each includes a micro USB cable, which is used to charge the block, and at least one USB port for power output; the BoostBloc 6600 has two USB ports to charge two devices at once.

In a recent test on a smartphone drained to 11 percent of its power, the BoostBloc 2000 gave the phone enough power to continue playing music for a couple of hours while still charging the phone back up to 92 percent.

For outdoor enthusiasts, Eton also offers the BoostTurbine 2000, a power charger with a hand-cranked generator that provides juice with a few turns of the wrist. A solar-powered charger also is available.

headphones let you SHAPE YOUR SOUND

Revo Wireless, $250,

www.jabra.com

Jabra, best known for its Bluetooth phone accessories, is making its first foray into Bluetooth premium headphones with the $250 Revo Wireless.

While the Revo has fashionably overstated bass sound, it also has an equalizer app so you can dial the bass down to a more realistic level -- or up to a brain-punishing thud.

Jabra works as if it were connected by cable; its sound is nearly indistinguishable from the $100 wired Revos. There were no dropouts or the watery sounds that plague some Bluetooth headphones.

The Revos feel solidly constructed of plastic and aluminum with faux leather earpads. Volume and song advance are controlled by a touch-pad surface on the left earpiece.

The real charm here is in the Jabra Sound app, which is available for Android and iOS. The app has settings for Dolby processing, mobile surround and an equalizer.

NEW YORK TIMES