Launched in 2011, Casascius Physical Bitcoins are physical metal coins with embedded private keys and Bitcoin addresses. Casascius coins are available in 1, 10, 25, 100, and 1000 BTC increments. The coins are designed such that they could be circulated in face-to-face transactions. The first person to redeem its private key gets the value on the coin, and afterwards, the coin no longer has any Bitcoin value. It is difficult or impossible to read the private key on the coin without damaging or destroying the hologram, which exposes a honeycomb-like tamper-evidence pattern when peeled.