Level Zero: Extraction Supporter Pack.
Packages
Level Zero: Extraction Supporter Pack
Features
Steam Achievements
Multi-player
Co-op
Online Co-op
PvP
Online PvP
Downloadable Content
Steam Trading Cards
Genres
Action
Indie
Massively Multiplayer
Adventure
Simulation
Overall, it's a set of in-game items. Not something really explicit here except for the weapons.