Most of what is known about Line Installation 9-12 is inferred from known facts about Line Installation 1-4. The installation likely served as a Flood research facility and a defensive installation. It possessed a battery of powerful energy cannons capable even of downing capital ships in slipspace. The weapon batteries are extremely effective, with one relatively small area littered with the hulls of at least a dozen crashed starships. The Installation presumably had its own Monitor in addition to a sizable force of Sentinels and special Gatherer units under its command. The Installation itself is a vast underground complex with tunnels and hallways reaching kilometers deep.
The installation destroyed hundreds if not thousands of starships between the time of its construction and 2558. It was rediscovered by post-war scavengers whose vessel was forced down onto the planet's surface. The scavengers set up a camp in the debris field and began to loot treasure trove of wrecked human, Covenant and unidentified vessels. However, they were unable to find a way off the world before their supplies ran out. By the time ONI pioneer teams arrived and began long-range scans of the planet, it was devoid of any signs of life.
- Halo 4 (First appearance)