This is a capacity expansion cartridge for the Mega CD. This unit has been stored in a dark place for many years, and the label is almost completely free of peeling or discoloration, and the terminal contacts are also in very clean condition. Condition: The exterior shows little signs of use and is in beautiful condition. Regarding operation: Currently, I do not have a Mega CD unit on hand, so I have not checked for operation or data retention. Notes: This is a precision device that has been in use for over 30 years, and the life of the internal battery is also unknown, so it will be sold as-is and considered junk. Recommended for those who want to obtain a valuable genuine product in a beautiful condition, and those who can perform maintenance such as battery replacement themselves.