With a door spy , it is possible to see who is standing outside your door without them being able to see you. A door spy should give you more safety and security, because with a door spy you can see who is knocking on your door before you open the door.
You can get door spies in many different colors and sizes, in addition they can have different functions, the normal one where you can look out and see them on the other side without them being able to see you. However, you can also get digital door sp