A security company based in Washington revealed its design for a door that they say would make buildings less vulnerable to gunmen who want to get in.
Barbecan Security invented the "linear revolving door."
The door has technology similar to locks on a river or air locks on a submarine.
People walk through the bullet proof sections that also has metal detectors.
Only one door is open at a time, but they are synchronized to allow traffic to flow smoothly.
Once inside the section, the person is scanned for weapons or explosives. If they're cleared, the second door opens and they can move through.
Otherwise, they are locked in.