... Speaker with Casters USB SD MP3Mobile and active PA system with 12" (30cm) bass driver and 100W amplifier power45W RMS ... .3 mm jack, microphone input, 1 x RCA stereo line input, 1 x 12V terminal connectionPlayable formats: MP3, WMAFrequency ... Conference, classroom, military training, guide, sales promotion, public sale's loudspeaker recorder play. *Pageant, congregation, make a speech, traffic command, ...