[Dual Function]: Can be used as door stopper alarm and door stopper, its highly cushioned rubber bearing can prevent the door from sliding and prevent bad guys. Protection around you. Can be used at home and while traveling. [3 levels of sensitivities]: high - medium - low sensitivity. It depends on the distance between the door and the door stopper. [Loud Alarm]: Intruders try to open the door, the wedge-shaped design will prevent it from opening and activate a 120dB alarm. [Powered by 9V battery]: The door stopper alarm is powered by 9V battery, one piece can be used for one year under normal circumstances. Very convenient. (Note: battery not included). [Easy to use]: No installation required] Just place the alarm behind any door (home, hotel, etc.). Very convenient to take with you when traveling or staying alone. A must for you. Especially for girls