The PlayStation 2 Expansion Bay is a 3.5" drive bay introduced with the model 30000 and 50000 PlayStation 2 designed for the network adaptor and internal hard disk drive (HDD). These peripherals enhance the capabilities of the PS2 to allow online play and other features that were shown at E3 2001.

The PlayStation 2 (PS2) is a home video game console developed and marketed by Sony Computer Entertainment. It was first released in Japan on 4 March 2000, in North America on 26 October 2000, in Europe on 24 November 2000, and in Australia on 30 November 2000. It is the successor to the PlayStation, as well as the second installment in the PlayStation brand of consoles. As a sixth-generation console, it competed with Nintendo's GameCube, Sega's Dreamcast, and Microsoft's Xbox. It is the best-selling video game console of all time, having sold over 155 million units worldwide, nearly triple the combined sales of the Dreamcast, GameCube, and Xbox.