I got these and a case free with my Sony Walkman. They are really light, and they don't need batteries, they just run from whatever they're plugged into, even an MP3 player with ONE AAA battery!
They may be light, but they are deceptively big, and when they are attached together by the bottoms they're quite big - ok if you're using a bag, I suppose.
The sound quality is a mixed bag, and it depends on what they're plugged into. For things that run on next no no power and are so light, the bass is quite good, just so long as you don't expect huge amounts of it! Also, unless what they're plugged into goes reaally loud, these are quite quiet, so you might not be able to hear them in a looud room or on a train or something. They are clear, however, and voices sound great on them.
So overall, they're great - when there's no better alternative or no power supply. And they are very cheap.
