Small and easily attachable, I managed to fit it on my hard hat I 4GB mp3 and more autonomy music 8:00 am everywhere, better than the radio or a post I put the volume to 12 / 40, my helmet isolate myself from the noise and I hear my music with unmatched quality !!! Finally I'm satisfied, the only fault I can find him is that the selection of song and a bit slow, the transition from one song to another can not do this on the fly.