The grenade-size SRS-XB10 is the smallest and most basic of the new speakers in Sony's line of Extra Bass Bluetooth speakers. At this size "extra bass" might be a stretch, but it does have a bit more punch than many competitors.
Available in multiple colors -- Sony sent us a review sample of the more mundane-looking black version -- the water-resistant speaker's claim to fame is that it has good battery life for a tiny speaker and delivers relatively richer sound than the plethora of other tiny Bluetooth speakers on the market.
The speaker has a few extra features worth noting: The detachable strap, which could be used to hang the speaker from a hook in your shower or from a tree branch, converts into a stand for the speaker when you place it on its side in horizontal mode. You can also pair two of these speakers and use them as stereo speakers for your computer, for instance (you get more directional sound with the speaker on its side).
The step-up models in the line -- the SRS-XB20, SRS-XB-30 and-- have special lighting effects, with the two top-end models delivering "clublike lighting effects with an LED perimeter line-light, a strobe flash and speaker light." The XB10 doesn't light up; it's all about its sound.
As far as that sound goes, for this type of little mono speaker, it doesn't get much better. It's still not great and the speaker distorts at higher volumes and with certain bass frequencies (the Shaun Frank remix of the Chainsmokers' "Closer" track has been rough on little speakers, including this one). But it does have a little punch to it and sounds decent with less complicated tracks and acoustical music. These tiny Bluetooth speakers are strongest in the midrange (vocals), so this would do well with movie dialogue and podcasts.
My only design nitpick is that the speaker's rubberized, soft-to-the touch finish attracts some dust and lint. On the plus side, the base of the XB10 has enough grip to it to keep the speaker from sliding around when you pump up the volume and it vibrates thanks to its built-in passive bass radiator.