From Sega Retro

The Everdrive family is a series of flash cartridges which allow ROMs to be played from SD cards (or in some cases USB) on original hardware. Depending on the model and console, other features may also be included.

Everdrive cartridges are sold as PCBs, which are often then repackaged in plastic shells and boxes by other companies to protect the contents.

Multiple variants exist:

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