Features:*110 decibel loud alarm goes off when door or window opens and it will not stop even the door closed, effectively helps deter intruder and alert residence. The wireless window sensors will give you peace of mind.*4-in-1 Mode: 1. General alarm (alarm stop if door closed); 2. Constant Alarm (constant alarm even door closed); 3. Closing-door Alert (sound Di..Di from 0dB to 110dB); 4. Door Open Chime (sounds DingDong once if door opens), can be used as a doorbell. Super easy to set the mode according to your need.*Come with LR44 batteries for each alarm sensor. Low battery consumption, battery can last up to one year. And it have low battery indicator, indicator light blink once every second and DuDu sounds every half hour to remind you to replace battery.*Light-weight and small alarm ideal intrusion warning for kinds of doors and windows (sliding doors/windows, hung doors/windows, crank doors/windows), cabinets, drawers,