describe Dual Function: Can be used as a door stop alarm and door stop, its high buffer rubber bearing prevents the door from sliding and keeps the bad guys out. protect your side. Can be used at home and while traveling. [3-level sensitivity]: high-medium-low sensitivity. It depends on the distance between the door and the door stop. [Loud Alarm]: The intruder tries to open the door, the wedge-shaped design prevents it from opening and activates the 120dB alarm. 9V battery power supply: The door stop alarm is powered by 9V battery, under normal circumstances, one piece can be used for one year. very convenient. (Note: Batteries are not included). [Easy to use]: No installation required] Just place the siren behind any door (home, hotel, etc.). It is very convenient to take with you when traveling or staying alone. A must for you. especially for girls