Transporter Windows are a mechanism that allow the player to instantaneously travel between two or more fixed point through otherwise impenetrable barriers.
The inside of the observation window reflects that of the view through its corresponding window. If the player moves close enough to the transporter window so that it fills their screen they will be transported to the position the view inside the window would be seen from.
After transportation the view will remain the same but now matching its surrounding. The view inside the transporter window will now match what is directly in front of it but has not changed. This transportation effect will go unnoticed by the player until they back away from the window and notice their surroundings have changed, although a Matter Gun will reflect the room color immediately.
Now the transporter window will be inactive, reflecting the view directly in front of it as if it were transparent. The player can reset the transporter window by moving around to the other side so that the first is no longer visible and the view will have changed. This technique be used to travel to other destinations on some transporter windows.