iTour-20 Portable Pocket Sized Speaker for iPhone, iPod, MP3 players, laptop, Smartphones and more (Color: Black) Performance ultra portable 2.8W speaker for portable audio sources such as mobile phones, iPod, netbook/notebook/macbook Integrated Class-D amplifier for excellent acoustic performance Pop-in/out-mechanic: Pushing upper and lower part together reduces its size to fit any pocket. The extended mode guarantees best sound performance. Integrated Li-Ion-battery (USB chargeable) for upto 5 hours playtime Vaccum Bass: Small in size but big in bass