Perfect for the home, office, sheds, garages and more - this Window and Door Alarm has a 120 dB alarm siren when a window or door is opened. There is an easy access off/alarm/chime switch as well as a low battery test button. To arm the unit, locate OFF/CHIME/ALARM switch on the side, slide the switch to the desired position. If the protected window or door is opened, the alarm siren will sound continuously until disarmed or when the door or window is closed. When in the chime position, if the door or window is opened, the chime will sound. It will sound once again when the door or window is closed and reopened.