This is the groundbreaking Aircurve Acoustic Amplifier; By simply putting your iPhone into the slot & turning it on, with absolutely no outside power source whatsoever, the volume of the music being played is amplified by about ten decibels! Fear not, no witches are at work here though, it's just brilliant innovative technology that, through mathematic precision, means the coiled waveguide "horn" within the Amplifier takes the sound from your iPhone & disperses it, more loudly, around the room! So no need for batteries with the Aircurve Acoustic Amplifier, it doesn't even use any of your phone charge. The considerate inventors have even created a slot so the device can be charged or synced whilst playing your music, & the transparent frame of the Aircurve Acoustic Amplifier means you can see all the curves in the horn working their magic as it blasts out your favourite songs! What more could you ask for?