From the Squidoo Barbie Girls Lens:

To get the full experience of the BarbieGirls.com world, girls will want to own the Barbie Girls MP3 player. This device can be connected to the computer to unlock exclusive pets, hangout spots, furniture, games, and more.

The Barbie Girls MP3 player is a 4½-inch portable device that is a music player and fashion doll in one. The Barbie Girl device is sold with a belt clip, docking station, adjustable earbuds, durable storage case, and two sets of interchangeable hairstyles, faces, tops, skirts, and shoes. Additional packs of outfits, accessories, and pets will be sold separately.

The Barbie Girl music player will play any non-DRM-encrypted MP3 or WMA files, and will have 512 MB of on-board memory, enough for approximately 120 MP3 or 240 WMA-file songs. Memory is expandable to up to 2 GB with a miniSD memory card (sold separately). The device comes with Windows Media Player 11 and runs on a built-in rechargeable lithium polymer battery that is charged via a USB port.

From the BarbieGirls Squidoo Lens:

BarbieGirls.com has a strong focus on safety for the young girls interacting on the site.

All registered users can use B Chat, which is automatically filtered to only allow language that is already in the site’s database of accepted words. This filtering prevents girls from giving out personal information or using abusive or foul language.

Girls who have the Barbie Girls MP3 player can dock the player at the computer of a friend they know in the real world, which allows them to be designated on the site as best friends. Best friends are then permitted to engage in Secret B Chat, which is private and filtered only for obscene and abusive language.