Storage Box

The Storage Box is the puzzle item of the Mail Room in The Archives, a lid-and-base cardboard archive box with a front label. Boxes are scattered through dedicated storage areas, mostly on shelves with a few on the ground, and each segment of the room has depots labeled with serial numbers made of one letter followed by three digits.

The sorting puzzle

Every box carries its own randomly assigned serial number, and among them are the ones that match the depots in that segment. The player has to find the box whose number matches a depot and place it there. When every box is correctly placed, the door to the next room opens. The wiki says a box takes both hands and does not occupy an inventory slot, so the player cannot switch items while carrying one.

Archival Storage

In Archival Storage the boxes have no serial numbers and cannot be picked up; they are decoration. One specific box, however, tunnel-visions the player and plays a cutscene when approached, awarding the Who Am I? achievement.

Taking one out

A box can leave The Archives. Lighting a Flare and then grabbing a box stores the box in the inventory instead, and a player who finishes the fourth room can pass the final gate before Honcho catches up. Once out, the box can go into a Rift. A box in The Hotel was shown labeled ERR-0.