Why three? Of course Sony targeting three different segment. The S-series available in 4GB and 8GB that’s priced at $150 and $180 respectively. The E series also available in two different storage capacities 4GB and 8GB with pricing set at $100 and $140 respectively. And finally the B series also coming in the same storage configuration and costs only $45 and $60 respectively.
So what is the different between all the series? The S series as the most expensive one features noise canceling, video and MP3 players. In the middle, E series doesn’t have noise canceling, and finally the B series able to play MP3 only.