They were physical bitcoins worth 100 Bitcoin, 50 Bitcoin, 25 Bitcoin, 10 Bitcoin, 5 Bitcoin, 1 Bitcoin, etc. A couple of years ago. But the state did not like them, so they made them stop. They had the private keys under like scratch-off holograms, so you could tell if it had been tampered with, in which case it would not be acceptable. But as long as that private key was intact, you knew for a fact that it had the amount of Bitcoin on it that it said it did. Since they were physical and had the private keys associated with the physical coin object themselves, it was totally off-chain and therefore needed no electricity to trade.