CBS Local — A Wisconsin high school student has developed a tool he hopes will save lives during a mass shooting. Somerset High School’s Justin Rivard created the “JustinKase” in his shop class after being motivated by recent deadly school shootings.

Rivard’s invention is a unique door jam made of steel plates and connecting rods that the student designed to slide under classroom doors and keep them from being opened. “This is the thing that can save thousands of lives if it’s used properly,” the high school senior told CBS Minnesota in January.

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Rivard took the JustinKase to every teacher and classroom in his school and tested his invention against the strongest people in the building, but no one has reportedly been able to open a door while using his device.

“You can lock a door with a lock, it can get shot out. You can lock a door with this, it can’t get shot out. You can’t get around it,” Rivard said, via USA Today. The JustinKase has even stood up to linemen from Somerset’s football team, who failed to push their way into the rooms.

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“I think it’s a game changer,” said Principal Shannon Donnelly, who helped Rivard land his first customer for the JustinKase: the Somerset Board of Education. “We immediately, within a week of having these, went through an entire drill, all throughout the building, really walking through students and staff,” Principal Donnelly added.

The student’s website, which is now selling the device for $95, promotes the JustinKase as the solution for defenseless classrooms trying to keep an active shooter outside during an emergency. The JustinKase has garnered national attention after a mass shooting killed 17 people in a Florida high school on Valentine’s Day.

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Somerset has also ordered the JustinKase for it’s middle and elementary schools. The nearby Grantsburg School District has also put Justin Rivard’s growing company to work with an order of 100 door jams as well.