Introduction: Extra loud alarm. 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 120 dB alarm. The alarm will scare off the would-be intruder and alert you to the attempted entry. Door stop alarm & door stopper keep intruders out, also prevent the doorknob from hitting the wall. High- quality: Made of high damping rubber & abs plastic, very convenient to use. Loud alarm: 120dB loud alarm sound could scare intruder. Portable alert 3 sensitivity levels: Low - Medium - High, with an adjustable sensitivity switch on the side. Easy to Install: Portable and easy way to add piece of mind when traveling or working alone. Widely use: Can be used in home, dorm, office hotel, motel & more. Specification: Powered by:1* 9v battery (not included) Single size: 5.5 * 1.8 * 1.6 inch Single weight: 0.25 lb Package includes: 1 x Door stop alarms (9v battery is not included.) [Dual Function]: Can be used as a door stop alarm and door stopper, Its high damping rubber bearing can prevent the door sliding and prevent the bad guys into. A protector around you. Can be used in home and travel. [3 Level of Sensitivities]: Hige-Midium- Low Sensitivities. Which depends on the distance door touch the door stop alarm. [Loud Alarm]: Very loud shrill that would definitely scare someone away with 120db alarm. Weight: 0.25 lb [Powered by 9V Battery]: The door stop alarm powered by 9V battery, One piece can be used for a year under normal circumstances. Very practical. (Note: Battery not include) [Easy to Use]: NO installation required, Simply place the alarm behind any door (home, hotel, etc). very convenient to take with you when travel or stay indoor alone. A really must have around you.