Unlike the Enigma, which used lamps for the letters, it worked with two reels of paper; the encryption process involved turning the drum through 360 degrees with the attached crank handle. This rotated six cipher wheels, rather than the previous three, of differing sizes, in a highly irregular motion, sometimes even backwards. Moreover, the position of one wheel affected the movement of the others. The recipient had to set the wheels in the identical starting position before entering the encrypted text. The plain text and the encrypted message were printed in parallel on two strips of paper. Of the 11,000 devices ordered, only approximately 500 units were shipped to the Abwehr, or military intelligence service, and another 1,000 to the weather service, from October 1944. However, the latter was supplied with the SG-41Z numerical version, with numbers instead of letter keys. Weighing in at 13 kilos, the SG-41 was deemed too heavy for front line use.
Even the experts in England failed to reconstruct – and thus decipher – the SG- 41 by the end of the war. Accordingly, the allies described the cipher machine with deference as a "remarkable machine". According to the cryptology expert Klaus Kopacz, had this new encryption technique been deployed earlier, it would probably have extended World War II by approximately two years, although it is unlikely to have affected the outcome.