Imperial code cylinder Palpatine ' s Galactic Empire used specific code cylinders to provide its officers with security clearance codes . In combination with the rank plaques , these code cylinders were also used to denote rank within the hierarchy . Imperial code cylinders were introduced since the early days of the new regime , and they remained in use among the Imperial splinter factions after the Empire collapsed at the Battle of Endor . Overview . Imperial code cylinders were among the most common access tools employed by the Galactic Empire . Standing regulations demanded that every Imperial officer ' s code cylinders were in view at all time , and they were kept in narrow pockets on either side of the upper chest . However , only high ranking officers displayed them on their jacket ; Imperial engineers and technicians wore them in special pockets around their neck or on their belt . Imperial installations were divided into a variety of sectors , each separated from others by security checkpoints . At major checkpoints , officers who wished to access the next secured area had to prove their identity and rank by inserting individualized cylinders into a scomp link . The scomp link interfaced with a centralized computer , which determined whether the officer had the proper clearance before denying or approving their access request . Due to their use , Imperial code cylinders enforced discipline among the lower ranks and contributed to the insignia of officers and subofficers by indicating seniority . All officers of the Navy and Army were issued with at least one cylinder , which they were ordered to display at all time . A second device was sometimes issued when an officer ' s duty spanned a number of unrelated sectors . Admirals of the Fleet were usually issued with three code cylinders , which enabled them to access the intelligence databanks carried by capital ships . Because each cylinder permitted access to only specific sectors , high - ranking officers carried up to four of them . Aboard the first Death Star , Grand Moff Wilhuff Tarkin possessed four cylinders , which allowed him to travel freely throughout the moon - sized battle station . In contrast , General Cassio Tagge and Admiral Conan Antonio Motti carried only three code cylinders . While some officers considered the cylinders a mere mark of their status , the devices were also programmed to give the Empire a detailed knowledge of its servicemen ' s actions . The Imperial computer network kept detailed records of every cylinder ' s activity , including every time a sensitive file was accessed or a high - security area was entered . Such logs were monitored by agents of the Imperial Security Bureau who scanned the records in search of suspicious behavior — including over - frequent access to a secured file or area . Characteristics . The Imperial code cylinders came in at least three different shapes , as the ones worn by Grand Moff Tarkin , Admiral Motti and the Stormtrooper officers were significantly distinct . The most common type of cylinders looked like thin pens with a small pocket clip and a blue tip containing the series code . Those worn by the Stormtrooper corps were shorter , with a different pocket clip . Admiral Motti ' s cylinder were thicker and featured a spiral drill bulb at the top , which was in fact the computer link itself . History . The Galactic Empire used code cylinders from its early days on . When the Galactic Emperor gathered most influential officers in order to introduce them to his new second - in - command , Darth Vader , all of them already wore at least one code cylinder . After the Empire collapsed at the Battle of Endor , code cylinders remained in use in surviving Imperial outposts . The New Republic , the democratic government established by the Rebel Alliance , also started to use similar coded cards or pass - keys to verify an individual ' s identity . Behind the scenes . The code cylinders used by the Galactic Empire first appeared in , the first installment of the " Star Wars " original trilogy . In the movies , some of the Imperial code cylinders were small pen - like radiation . However , the Stormtrooper cylinders that were shown in " " were in fact chalk holders that were provided to David West Reynolds by Mathew Clayson .