Feel free to move if this is not the right place. I wonder what on Earth this thing is, and does it really work? How can it "add" colours? Well, at least it will protect the GOLD FINGERS of my games.
The Gameboy Colour has colour pallets for the games it plays. This device allows you to change it. It's like the way one of the Snes GB players allows you to add some colour changes to it. I'd say give it a shot, but that requires opening it. Neat device regardless.
Thanks man. Found a page with a few screenshots of Bubble Bobble: https://gallowsmart.wordpress.com/tag/magic-color-card-ii/ I found 2 variants which are probably the same hardware with different shells. One by MADCOW One by Y2K
That's colour cartridge is a neat device. It's just a shame it sticks out too much when plugged in to a GBA SP.