The 2-Factor Storage Bar uses complex two factor authentication to access the stored BTC value once it is sent to the bar. These bars have their public address laser printed onto them, as well as ‘casascius.com/2factor’ which explains how the bars work.
In order to redeem the bar, one must not only tear the hologram to retrieve the private key, but combine it with another code rovided at purchase. If a 2-Factor bar is sold, the seller will have the other part of the code, but is not able to access the funds as long as the hologram is intact.
For an unknown reason, all the first-bits appear to be intentionally obscured by black pen markings.