Shenzhen’s underground system is new, just like the city itself, and has some interesting quirks.

For example: locals use their RFID-enabled passes, the sort of contactless system familiar that’s now familiar all over the world but was pioneered just across the border in Hong Kong with the Octopus card.

Visitors, however, receive these little tokens.

Despite looking like simple plastic coins, these things actually contain an RFID chip as well. They contain the relevant amount of credit for the trip you have bought, and you swipe them at the gates on entry, before paying them into the gates (like coins) on exit.

(I assume they are, at that point, wiped clean and recycled back into the system.)

It’s an interesting combination traditional and hypermodern forms of money.