Uhh... that's actually a fake cartridge- Pokemon Green was never released outside out Japan. While it would be interesting to see what's on the cartridge, I'd hate to be the sucker that pays $300 plus an extra $100 for shipping.
Since there's not much left to discuss in this thread, I'm going to close it. And just for future reference, even if you aren't the one selling the item, please don't post links to eBay unless it's relevant to the discussion, or it might be seen as advertising. Thanks!
CLOSED.