MUSCATINE, IA (NBC) - A group of educators in Iowa have created a device they say can help save lives during an active shooter situation at a school.
It's a simple metal piece that is slipped on a door closer and can resist up to 550 pounds of force.
Daniel Nietzel is a teacher in Muscatine. He says the slam of a locker makes him worry it could be a shooter.
He wanted to take it into his own hands and came up with the invention "The Sleeve".
Eventually, he and four other educators created fighting chance solutions.
Right now, most classroom doors only lock from the outside, and during the Sandy Hook shooting, a teacher was shot when she stepped into the hallway to lock the door.
This new invention works to prevent that. It quickly slips on to keep the shooter out, and comes off in one second for evacuation.
To top it all, they've made it affordable for teachers, to put in their own classrooms even if school districts won't fund it.