BASED ON PRIVATE KEYS. Each Opendime holds one private key. It publishes the public key (payment address) to anyone and never reveals the key until "unsealed".
PIGGY-BANK ECONOMICS. It's like a piggy-bank. You must destroy it to spend the funds. At first that seems expensive and wasteful, but it's a key part of our security model: you can trust a sealed Opendime, and it's obvious when it's been opened.
INSTANT AND OFF-CHAIN. Since we are putting private keys into a physical form you can trust, you can simply hand around Opendime units to move amounts around. There are no pre-defined Bitcoin amounts with Opendime either. Store as much or as little as needed.