The Transvertex HC-9 was a mechanical encryption device invented in the early 1950s and used by the Swedish Armed Forces from 1964 to 1994. The encryption key consist of a punch card and an alphabet sheet wrapped around a drum. These would have been replaced on a regular schedule. Decoding a message also required a five-character message key that was used to set the starting point for the five cipher wheels. The encoded message key was placed at the beginning of the message. For each letter in the message, the operator turned the large metal trigger knob on the left side of the machine. This turned the five cipher wheels one step. Based on the pins blocked by the punch card and some hardware logic, the cipher wheels determined which alphabet was displayed in the window at the front. The message was decoded by matching letters in the displayed alphabet with the corresponding letters printed above and below the window. (The entry for the HC-9 at the Crypto Museum website gives a much fuller explanation with diagrams.)

The text printed on the punch card, TOTAL-UTB NR 2, indicates that this card was used for training purposes.