Durable with High QualityThe door stop alarm is made of large ABS plastic and stainless steel plate. Excellent performance in terms of quality and service period. Attention the gap between the door and the floor should be at least 10-35mm for its normal operation. Easy OperationThere is an ON/OFF key on the door stopper alarm. Just place the alarm under the door and turn on the switch and it will start working. As soon as an intruder tries to enter, the door stop alarm will immediately go off and sound a 120dB alarm . Adjustable Sensitivity LevelsAdjust the sensitivity of the door security alarm - low, medium and high. Choose the levels according to your needs. Set the level high when you sleep and you will know the subtle differences of your door and get peace of mind. Excellent DesignThe shock absorber rubber at the bottom can prevent the door from sliding when someone shoot. Remember to push it firmly under the door when using. It is not recommended to use it on too smooth floors (like tile/laminate/wood) or to set a high sensitivity level if necessary. Can be used as a normal door stopper when it turns off the switch and keeps the doors in the correct position. Protect your SecurityOnly requires a 9V battery (NOT included). Lightweight (110g)/pack and convenient to carry and protect your safety no matter when you are at home or traveling. Best used in doors that open inwards (like hotels). Feel comfortable even when you are in an unfamiliar place. Product Open the back cover, install a 9V battery Choose the sensitivity according to your situation Turn on (when off, it can be door stop without alarm) Put it under the door to work. If the door is installed very high and far from the floor, please put a soft object under the door stopper. Feature High quality: Made of High absorption rubber and ABS, very comfortable to use. Loud alarm: 120dB alarm sound can scare off intruders. Portable alarm with 3 sensitivity levels: Low, Medium, High, with an adjustable sensitivity switch on the side. Easy Setup: Portable and easy to take on a trip or work alone. Widely Used: It can be used at home, bedroom, office, hotel, motel, etc.