With parents across the country worrying about the safety of their kids after the latest school shooting, one company thinks they have the solution. They have developed a contraption that would protect school entrances from armed invaders. The newly-patented device is a metal detector, x-ray machine, bullet-proof barricade and an armed guard all in one called the Linear Revolving Door. The door is a long hallway with two sliding doors that are never open at the same time. After passing through the first door, it closes behind the person. Then, they walk past a metal and explosives detector in order to get the second door to open. If the person does not pass, the second door, which is bulletproof, slides back and pushes the intruder out of the building. The idea for the door started in 2007 after the Virginia Tech shootings. The developers believe that gun control, or a human armed guard is not the answer. The technology could be used in airports, schools, military bases, malls and more.