A mantrap, in modern world, means a small room that is encased or made-of metal, and contains two or more doors. The principal rule is that both doors cannot be open at the same time.

If a person needs to access a facility, he must access it through a mantrap. He might use a keycard to open the first door, then enter the mantrap and close the door behind him, and only then he can enter his personal PIN (for an example, could be biometric as well) which, if entered correctly, will open the second door.

Failure to enter the PIN code, or trying to force either of the doors open, will trigger an alarm. An intercom system will be activated, and an announcer will notify that a guard-team has been dispatched to clear the solution, and apprehend the suspect to the police.

Such "boxes" usually also contain tailgate-prevention technologies, so that only one person can enter at a time.

In history, mantraps could also cause deadly forces at the intruder, possibly by using a sleeping-gas, impaling spikes or emitting a high-energy noise. Such are illegal today.

Mantraps are very scary to the people who rarely use them. The smell, the sounds... And when you enter a mantrap, the silence is somewhat disturbing. There's a set amount of time in which you need to enter your code, or an alarm will be triggered. This could be 10 seconds or less.

Most advanced mantraps enforce tailgating-prevention by tak...