Durable with High Quality:The door stopper alarm is made of great ABS plastic and stainless steel plate. Excellent performance in quality and service period. Mind the gap between the door and floor shall be at least 8-10mm for its normal operation. Easy Operation:There are ON/OFF key on the door stop alarm. Simply place the alarm under the door and turn on the switch and it will start to work.Once intruder tries to enter, door alarm stopper will be triggered at once and issues 125dB alarm. Adjustable Sensitive Levels:Adjust sensitivity of the door stop alarm-Low, Medium and High. Choose levels according to your need. Set high level when you are sleeping and you will know subtle differences of your door and get a peace of mind. Excellent Design:Damping rubber at the bottom can prevent door from slipping when someone pushes. Remember to push it tight under the door when using. It is not recommended to use it on too smooth floors(like tiled/laminate/wooden floor) or set high sensitive level if necessary. Can be used as a normal door stop when turns off the switch and hold doors in proper position. Lightweight(110g) and small size makes it easy to put in your purse and carry. Protect Your Security :Only requires a 9V battery(NOT supplied). Convenient to carry and protect your security no matter when you are at home or traveling. It is better to use in doors that opens inward(like hotels). Feel at ease even when you are alone.