Introduction: Extra loud alarm. Simply place the alarm behind any door. Should an intruder attempt to open the door, the wedge-shaped design prevents it from opening and triggers a 120 dB alarm. The alarm deters the intruder and alerts you to the break-in attempt. Features: Size: 14 x 4.5 x 3.8 cm Net weight: 96 g< /p> Gross weight: 128g Packaging: Various types Alarm volume: 120 dB Power supply: one 9V battery Note: The gap between the bottom of the door and the floor should be 1 to 3.5 cm.