They can be interior or exterior, however, most people use them for outdoor applications. They have an internal locking device that stops the individual slats from opening or closing. This is useful for closing up a porch area, keeping the wind from blowing the louvers opened or closed, and to keep little fingers from getting smushed if children are present. There is also an available locking pin option that goes into the floor to lock the doors into position and keep them from being opened from the outside. I would not say the locking pin is tamper proof. Again, the idea is, you will have locked doors going into the structure. I hope this helps!