Announced on September 6th of 2011, these coins were the first funded physical Bitcoins ever produced.
They are sought after both for their significance as the first coin of their type, but also due to the added perception of rarity due to a spelling error (Casascius is spelled as ‘CASACIUS’) in the small hologram text.
There are two special varieties of this coin. For one, 1,574 of these were actually funded in early 2012. Second, there is an ultra-rare type in which the firstbits are not in the middle, but significantly higher on the hologram. Only five of these exist.
In December of 2013, an image of fake holograms imitating the error emerged. This was the first counterfeiting related incident regarding physical crypto-currency.