mini speaker is used for mobile phone,computer,MP3/MP4player 1.Input:5.0V ... Output:3.7V 2.battery :800ma Stereo Built-in mini speaker is used ... for mobile phone,computer,MP3/MP4player1.Input:5.0V Output:3 ... of "audio in" you can play music sources from mobile phone ,MP3,MP4 PC and toher audio devices.5. ...