While substantially cheaper to produce than cartridges, the storage limitations of the format resulted in Sega publishing only a dozen games in the format (1986–1987) before moving to using solely game cartridges. The revised model of the Sega Master System, Sega Master System II had no Sega Card support, reflecting Sega's move away from the format.
There were four versions of the card.
- The original My Card was released for Sega's SG-1000 console (SG-1000 and SG-1000II) and SC-3000 series (SC-3000 and SC-3000H).
- The second version of the card was for the Sega's Japan-only Mark III. The Mark III is also backwards compatible with SG-1000 My Cards through the "Mega adapter" device.
- The third version of the card, called the "Sega Card" was released for the Master System, the international version of the Mark III. The Power Base Converter has a card slot allowing for use of the cards on the Mega Drive.
- The final version of the format was the My Card EP, a rewritable version that was test marketed only in Japan.
- Capacity up to 32KB
- Thickness of about 2mm size
- 36-pin (pin 17, pin 19 ground)