4 in 1 Mode: This alarm has 4 modes. 1. Timed Alarm (Di-Di-Di sound from 0 dB to 108 dB if the door is left open for 3/15/30/60 s); 2. General Alarm (alarm stops if the door is closed); 3. Constant Alarm (constant alarm even when the door is closed); 4. Door Chime ("DingDong" sound once the door is opened) 108 dB Loud Alarm: The door and window alarm helps effectively deter intruders/thieves with a loud 108 dB alarm. The door chime will also alert you if children/pets/elderly people arrive or leave unexpectedly. You can easily set the appropriate mode according to your needs Easy to Install: This home/window contact alarm security kit comes with self-adhesive pads, so no tools are required, just stick the door alarm sensor on the door or window. It can also be used as a door stop alarm, pool door alarm, garage door alarm, or sliding door alarm. Low-power design, providing convenient and long-term protection. They can work for more than 2 years Mini and Portable: With its mini design, this wireless alarm won't take up extra space. You can easily carry it in any backpack when you go out. (If the alarm doesn't work, check if it is in OFF mode or if the batteries need to be replaced.) Installation Note: Make sure to close the alarm and the magnetic strip, the installation distance between them should not exceed 0.78 inches. The 2 parts must be aligned by their alignment arrow