The marked room is the main room that will be contested in this building. This should be the first room you run to and unlock because if you receive high value loot you can quickly put it in your secure container before moving on or being contested. While the loot for this room was nerfed, it still will provide a great return on investment for the key.
Room 214 is the furthest north room on the second floor of the three-story dorms building. Inside the room, you will find a safe, loose loot, and a possible key spawn in the red mug for dorms room 203. When I loot this room, I typically only loot the safe for the money and possible rare items. There is no need to look for the key in the red mug as it has a very low value and is not worth it.
Room 204 is located on the opposite side of the building from room 214. In this room you will find a blue weapon locker and safe combo. The bottom part of the locker is the weapon locker where you will have a low chance of finding a high value weapon. On top of the weapon locker is a small safe where you can find cash and other rare items.
Room 105 is located on the first floor of the two-story dorms, and it is behind the fenced off section of the building. Because it is in the fenced off section of the building, you must enter from the southern outside door. Once inside, it is the last door on the left closest to the fence. Inside the room you will find a safe, provisions on the bed, and loose loot on the floor of the room.
Room 114 is conveniently located right across the hall from room 110 in the two-story dorms building. Once inside the room you will find a safe, a medcase, one computer and loose loot.
The factory exit key has a few uses on Customs that are very beneficial. This is a key you should never go without when running Customs. The Factory Exit Key opens "Shortcut" at new gas and the extract labeled "ZB-013" under fortress.