These light and cheap coins are the only nondenominated Casascius coins, and come with no hologram stickers or private keys. There is a slight indent on the back to make storing a private key under a personal sticker easier.
One popular function of the coins is for use as personal business cards; simply create a sticker of your contact details and put it on the back. This has been utilized by some Bitcoin companies.
Perhaps unexpectedly, these coins have been used as a medium by other coin producers to create pre-funded or unfunded physical crypto-currency for commercial purposes. These include SerpCoin, Cryptofreeze, AussieBTC, and others.
They are sold in packages of 500, and are the only item available through Casascius after normal production and sale of coins ended.These coins come in different