I've seen and used devices like these at various Federal facilities and you stay inside for 3-4 seconds until a guard pushes a button to open the other side. T

I've seen and used devices like these at various Federal facilities and you stay inside for 3-4 seconds until a guard pushes a button to open the other side. The guards called them scanners and said that they sniff for explosives. These look identical, so maybe sniffing is an add-on feature.