Xcellent Global 2 Pack Home Security Wedge Door Stop Alarm Security System M-HG025 by Xcellent Global Simply place the alarm behind any door. If an intruder attempts to open the door, the wedge-shaped design will prevent it from opening and activate a lound alarm. The alarm will scare off the would-be intruder and alert you to the attempted entry. An adjustable sensitivity switch prevents tampering. When traveling, just toss this lightweight unit in your luggage. 2 PACK inside. 1 x 9V Battery required but not include.