The card is meant to provide malware mitigation with our screenless products . It ' s a physical secret only you and the secure element know . It is also used to pair the dongle with a smartphone , in order to use the phone as a remote secure screen . The Nano S and the Blue don ' t have this security card since they embed a screen . If someone physically steals the device but doesn ' t know the PIN andor the passphrase which can be setup since firmware 1 . 2 , they won ' t be able to steal the coins . You on the other hand can restore your coins a new device thanks to your paper backup . U 2 F support means the device Nano S and Blue features a U 2 F application , which can be used to authenticate to Google , Dropbox etc . The U 2 F application , when started , technically transforms the device into a U 2 F dongle . You computer will see it as a completely different device technically we can also emulate a keyboard to type passwords , a CD drive , a sound card . applications on the S and the Blue a bit of imagination could give life to interesting projects