Now available from Top Notch Door + Hardware!

Finally, a solution for the school security problem of how to lock a door safely and securely during an emergency. Typical classroom function locksets require the teacher to step out into the hallway, lock the door, and return to the classroom. This exposes them to whatever situation is occurring in the school. Upgraded "classroom intruder" locksets are a step in the right direction, allowing the door to be locked from the inside. However, that still leaves a vulnerability... if a master key is taken from an administrator or janitor during the incident, the assailant now has full access to any door. 

The solution to this problem is a simple mechanical device that can secure the door in seconds, and that can not be opened from the outside. 
Versions are available for doors that swing into or out from the classroom or office.