1Built-in class amplifier,which means power is low consumed ,pure and exquisite timbre,working time:?2 hours 2)Electronic volume control avoids the signal interference and wastage which is from the mechanical friction,with this the units will perfectly reproduce sound. 3)The speaker is used highly efficiency,internal magnet,double rubidium iron boron as magnetic circuit system,completely improve the speaker's sensitivity.Anti-magnetic unit. 4)The stylish model design,line-in ipod jack,and it can play music simultaneity charge your iPod 5) It can work with MP3,CD,MD,IPOD,computer,personal stereo and any set,which has the audio output