Sega DreamCast Virtual Memory Unit (VMU)

You have memory cards and memory cards. The Sega VMU is a league on it’s own. Sega did a good job.

Sega DreamCast visual memory unit box front
Sega DreamCast Visual Memory Unit Box back
Sega DreamCast Visual Memory Unit Box side
DreamCast VMU in action with Crazy Taxi
DreamCast VMU in action with Sega Rally 2

Information:
https://en.wikipedia.org/wiki/VMU