ADVANCED TACTICS info.   So what exactly are EI (Expert Infantry) and Centurion levels?   These programs were designed for those who choose to take their armor above and beyond the minimum requirements for basic 501st Legion approval.  It gives you the chance to show a level of dedication and pride that takes your armor closer to being as "screen accurate" as possible, without as much extra work as you may realize.  (You may surprise yourself with what you are capable of)