The Memory Card (8 MB) Magic Gate is used to store settings, EyeToy video messages and savegames. Official Sony memory cards are only available at a size of 8 MB, the memory card came in black, crimson red, and ocean blue.
Later, Sony partnered with a third-party accessories company Katana to make Memory Cards that came in 16 MB and 32 MB. These Memory Cards were officially licensed products and has the PlayStation 2 logo, and says Magic Gate on them.
Third party memory cards are available up to 128 MB.