CD BackUp RAM Cart
From Sega Retro
The CD BackUp RAM Cart is a memory card designed for the Sega CD that plugs into the Genesis cartridge port. It resembles a regular Genesis cartridge, aside from a blue edging saying "Sega CD", as opposed to the usual red edging found on standard American Genesis cartridges. The unit contains 1024 blocks (1 MBit) of memory for game saves. Some RPGs - most notably Shining Force CD - used this for memory, as there was often not enough space for the save files in the internal backup RAM. In the case of Shining Force CD, this cartridge allows the player to unlock the last story segment of the game, unaccessible without the backup cart due to the Sega CD's internal memory limitations.