SC-3000 comes in different box layouts depending the edition and the distributors. Inside you can find the SC-3000, foam packages, user Manual, an AC Adaptor, RF Cable with a TV-GAME Switch (usually SEGA SS-55). No cartridges were included in the package.
 

SEGA SC-3000 Packaging

SEGA SC-3000 Black Version

SEGA SC-3000 White Version

SEGA SC-3000 Red Version

SEGA SC-3000 AC Adapter