Originally Posted by railroadtycoon
To add on something, the SF METRO CARD is more widely known as the PASSNET card on most of the non JR rail companies in the Tokyo metro area.
Tokyo Metro calls it the SF Card and Toei calls it the T-card, however they are all compatable on the Passnet system. Its a good prepaid card if you're using non JR lines.
Right, the name for the whole system is Passnet, but I think it's easier to people who don't read Japanese to look for the "SF" on the machine.