Hi, you can find more information, photos and diagrams for this on my website:
http://www.zx81stuff.org.uk/zx81/genera ... 4KRom.html
The board is the dk'Tronics 4K Graphics ROM card. I believe the reason that the card includes the word "Llamas" (and the ROM character set includes a llama character and one with the initials "JM") is because the character design was done by Jeff Minter of Llamatron fame. He discussed this in an article in Retro Gamer, I can't remember which issue though.
Cheers, Simon