Firmcoins are a new kind of currency. They can work as Casascius coins or Bitbills, but they are reusable.

You can load funds in a Firmcoin as if it were an hardware wallet, such as Trezor, and at any time you can unload the funds.

Also you can check if a Firmcoin has associated funds by querying the device. A Firmcoin proof it is has a private key, without revealing it.

site link: http://firmcoin.com/

Choose carefully any service that store and manage funds for you. Very few Bitcoin businesses offer enough insurances to be used to store money securely like a bank at this point.