Holograms.

Holograms are items rewarded from missions and dropped by enemies. They will either be opened, or encoded - in which case you will need to take them to Pedro to decode them.

There are common holograms, uncommon holograms, and rare holograms. (If I missed any, do add more)

Every hologram has a high chance of dropping an item of identical rarity, and a small chance of dropping an item with a rarity one higher. I.E. an uncommon (green) may drop a blue item.