Yup like Bad_ad said its one of the early messia 2 clones, these came from china and I saw a lot of premods with these, if it gives you hassle please replace it, these weren't the most reliable chips back in the day... http://www.mygamecards.com/goods.php?id=110
Many thanks. The chip works, the PS2 didn't. Refused to read discs, even after laser replacement and adjusting. Moved the chip to another PS2 yesterday and all works well.