The Sega Dreamcast Broadband Adapter (commonly abbreviated to BBA) was originally released in 2001 as an upgrade to the initial 33 and 56k modems which came with the system as standard. Another first, Sega was the first company to deliver broadband internet on a home console and due to the very limited release (only a few hundred thousand were released) the demand and price for these things remains high. These days, it can be used for homebrew as well as play the following Dreamcast games online.
Quake III Arena
Phantasy Star Online 1 & 2
Additionally, there was one additional colourway released for the Dreamcast and that was the "Pure Black" edition. The package is exactly the same as the regular version with the same dream passport. The only change is the colour of the BBA itself.