A clear plastic Yomega Stealth Raider in keychain size sold inside a plastic capsule. There were four keychain yo-yos in three color variations that you could collect. They included the following:
These excruciatingly cute Yomega's are miniatures of their full size siblings but without the actual hardware. Each version came with a short, ball chain attached to plastic calipers that went around the axle. It does not appear that they came with any specialized string to actually use the yo-yo. However, the instructions may explain how to string them.
To see all mini yo-yos in this museum, in the left panel, click Exhibits.
In the right pane, in the Name/Model field, type mini, then click Browse.