Features: No installation required Put it behind the door, pull the switch to ON, and enter the working induction state with a beep after 5 seconds. When someone pushes the door and the host senses-the vibration, the door resistance will automatically triggered the alarm, stop after 30 seconds, and enter the work again Sensing state. Very convenient to take with you when you travel Women can take it with them when they walk at night. When encountering bad guys, turn on the switch on the side and lightly touch the surfaces of the product to generate a vibration alarm to scare the bad guys away. The 130 dB active alarm continues to activate. Notice: 1.Actual color may be slightly different from the image due to different light effect. 2.Please allo1x Car Mist Freshenerw 1-3cm deviation due to manual measurement. Description Size: 9.8*4.35*2.8cm Weight: 43g Material: ABS Battery: LR44*3pcs Package List: 1x Doorstop Security-Alarm