【Durable with High Quality】The 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 Operation】There 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 Levels】Adjust 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 Design】The 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