It's gray, it's small, it's labeled "Game Converter," and it has a light blue ribbon attached to it; there's really nothing more generic than that. This 60-to-72-pins converter is probably the most generic of all the converters. You see them on auctions sites all the time.
 

The only upside to this one is its NTSC compatibility, yet the pins don't form a close enough contact sometimes to register the graphics (or the game) correctly.
 

Some of these converters are known to have come attached to Micro-Genius multi-carts. But to find one like that is extremely rare.