Ensure your emergency exit doors and used only for their intended purpose by installing the ASTI6400 exit stopper. The loud 97db alarm will sound continuously until the included key is inserted by authorized personnel. Deters shoplifters. Stops unauthorized employee use of fire exit doors. Lifetime guarantee on the durable casing. Affixes easily to practically any door using standard size screws. The ASTI6300 is also available for purchase. It does not include a keyed siren and will silence as soon as the door is closed. For best results and security, we recommend the 6400 keyed alarm model.