Per 
Item #: SCP-4233
Object Class: Safe(Keter)
Special Containment Procedures:
SCP-4233 Is to be kept locked by 2 pressure locks, one on each side. This is reinforced by a large steel padlock surrounding the handles of both doors. SCP-4233 is contained in a steel room with a lock only accessible by Level 5 Clearance Staff and a camera with constant surveillance of the doors. If the doors ever grow in size from their regular 2.3 meters high and 1 meter wide state, a defense team is to be set immediately.
Description:
SCP-4233 is a large steel double door standing at 2.3 meters high. Rust creeping around the edges with a worn and dirty finish to the surface of the doors. When opened, the door to the room is seen on the other side, inside the door. When entering the door, the subject cannot be seen behind the door, as if to not actually be there. As little farther testing has concluded, the door seems to lead to another instance of the foundation. The door on the other side is shown to be completely smooth and clean, with no rust or blemishes, as well as no locks to keep it closed - as it was on the real side after Incident 4233-a096. Being limited to only the cell room and with the door to the cell not operable from the inside, no further information was found until Expedition 1.
Addendum:
SCP-4233 has since been locked after Incident 4233-a096, with the opening of the door only available to Level 5 Clearance Staff.
Incident-4233-a096:
The steel double doors were opened from the other side on ██/██20██. A D-Class Personell frantically opened the doors, ran into the cell, and reclosed the doors. This D-Class we called SCP-4233-D-1. SCP-4233-D-1. Was seen banging on the cell door, begging to be let out. Approximately 4 seconds later there was a thundering thud against the door. The door handle began to turn slowly and when fully turned, what looked like SCP-096 burst out of the door and tore SCP-4233-D-1 to pieces. It was quickly confirmed that SCP-096 was still in his cell and that this was instead the instance of SCP-096 from the world on the other side of the door. The only difference with this version of SCP-096 was that it wore a black reflective mask.
With, what was named SCP-4233-096, still being able to see, it was assumed the mask was consisted of a 1 way mirror. Giving others the inability to see inside, but SCP-4233-096 the ability to see out. SCP-4233-096 returned through the door, and closed it behind him.
Expedition 1:
Soon after incident 4233-a096, a D-Class Personell, D-3378, was chosen to go inside the door to gather information from the other world.
D-3378 was given no information about incident 4233-a096 and went in completely blind of any knowledge of SCP-4233. D-3378 was equipped with a camera mounted on her left shoulder, an ear piece to hear and respond to the foundation, and a pistol.
Once D-3378 was on the other side of the door, the door was closed and locked behind her by three security personnel. D-3378 first commented on the fact that the door on the other side looked a lot nicer than on their side. Radio signals were having minor difficulties crossing through the door, and the video footage was very fuzzy back at control. Control asks subject to attempt to open the cell door. Subject replies that the door has a giant hole in it, continuing back through dozens of other walls. Control asks subject to leave the cell and look around. D-3378 leaves the cell and quickly screams with the first thing she sees. The camera and radio go to complete static and SCP-4233 is closed.
Footage is quickly rewinded and paused on a frame containing a humanoid figure with a long tongue pointed somewhere above the camera. Two minutes later there is a knocking on the door from the other side. The radio signal comes back up and D-3378's voice is heard asking for the door to be opened. Control beckons D-3378 to continue exploring on the other side of the door. D-3378 assures that there is nowhere else to go, the room outside the cell collapsed. The three security personnel suddenly walk over to the door and begin unlocking it without the okay from control. Control commands the personnel to stop immediately and go back to their posts. The personnel stop what they're doing and take a step back to their posts then pause and go back to unlocking the door. Two military personnel are quickly sent in to stop security from opening the doors. The soldiers open fire on the security, but the security personnel finish unlocking the door. The security members then collapse to the ground dead and the door begins to vibrate violently.
The steel doors begin growing in size and float up into the air. The door handles slowly turn and the doors angle down toward the ground. By this time, four more military personnel have been sent in with the cell door locked from behind. The steel doors open and a large transparent and gelatinous cube falls from the other side into the cell. Appendages grow from the cube and grab the door to pull itself back, but is suddenly squashed by a large black humanoid silhouette. Absolutely no features are visible except two bright white glowing eyes. From the creature's neck stretches a long black tongue, and on the end writhes D-3378. The creature's tongue is shown to be sticking in and out the other ear of D-3378. The soldiers begin firing at the creature. D-3378 is slammed to the ground with a loud crack as the bones shatter and the body becomes lifeless, then thrown at the soldiers, releasing from the tongue. The creature then quickly sticks its tongue through five of the soldiers, while the last one rolls out of the way and cuts off the end of the tongue with a knife. The creatures squeals in pain and retracts its tongue back, picks up the remaining soldier with it and pulls itself back through the door. The door begins to shrink back down and float back to its place.
The five remaining soldiers stumble to their feet and attempt to close the door behind. The soldiers successfully close the door and are then taken out to be examined by foundation doctors. The four bodies left in the room are also taken out for examination.
