Finally a Light Weight, Easy to Carry School and Work Protection Device, the product is manufactured to withstand and hold doors closed (The Jammer is not a substitute for a door lock). Sadly we hear all too often about Violence at our schools and workplaces, where great people fall victim to some crazed attacker(s). The theory for this device is simple. Stop unwanted entry into an office or school room or any inward opening door for that matter, such as Home, Apartment or Hotel Rooms. This device made by Door Jammer and combined with a VAS First Response Door/Carry Pouch is light enough to carry daily, and small enough to fit in your desk or file drawer. In an emergency, if it is safe, always evacuate, quickly get as far away as possible , yet due to circumstances you might find your evacuation route cut off or unsafe to attempt to evacuate. This where the device becomes important, all too often an available room does not have a lock or you do not have the key. The door jammer works quickly to install on almost any door (we would recommend that you already have it adjusted for your particular door). This could prevent or delay entry in a matter of seconds. If you find yourself trapped in a bad situation, secure the door, and hide behind cover if at all possible, shielding yourself from view, and if at all possible put as much as you can between you and the door and any windows. The Door Jammer is a Security Aid, and is not a substitute for a door lock, should never be your only solution, Plan now (Cell Phones, Water, Whistles, Office Design, what furniture can be used as a blockade) and be prepared, preparation can bring peace of mind. Important Never use on Fire Doors or Emergency Exit Doors, and make sure your door opens inward (towards the inside of the room).