From the Publisher:

The Rebel Alliance Officer & Agent pack allows players to build two customized Rebel Alliance characters that can be used as either a Commander or Operative when building their Rebel Alliance armies.

This pack includes over 20 optional parts players can choose from when assembling their miniatures, allowing for a huge range of personal customization for each character. Players also customize their Rebel Officer and Agent’s in-game abilities using the 9 unique Upgrade cards included in this expansion. Each of these unique upgrades dramatically changes the battlefield role, abilities, and synergies the character brings to the army.