Mini Size Alarm: Compact design, smaller than most of door alarms. DIY installation, just Peel & Stick. It is easy to mount this alarm on any kinds of doors and windows.110dB Loud Alarm: Under constant alarm mode, once triggered, Continued alarm will be a great deterrence to any thieves and intruders. Under doorbell mode, loud sound will be a effective and prompt reminder when your kids or pets sneak out of house.4 Working Modes: General Alarm, Constant Alarm, Closing Door Alert, Doorbell mode. Just toggle ON/OFF switch up and down to set modes. Each mode corresponds to a different tone. Please refer to the product picture for details.Wide Applications: Not only suitable for all kinds of doors and windows, such as hinged doors, roller doors and sliding doors, but also for refrigerators, drawers, filing cabinets, safes, garage, RV, office, warehouse, store and so on.Low Battery Indication: Comes with 3 pcs LR44 batteries. Low battery consumption and long standby time. It will sound "Du Du" every half hour when alarm is under low battery status.Advantages:Small Size & LightweightQuality ABS Material110dB Loud Alarm4 Working ModesDIY Installation, Peel and stickEasy To Use3x LR44 batteries IncludedLow Battery IndicationProduct Parameters:Alarm Dimensions: 56x33x17 mm(2.2x1.3x0.7 inch)Magnetic Bar Dimensions: 35x11x11 mm(1.4x0.4x0.4 inch)Power supply for alarm: 3 x LR44 batteries(Included)What You Will Get: 2/4/10 Pack of AlarmsInstallation Instruction1) Attach double-sided tape on back of alarm and magnetic bar, then stick them on 2 sides of seam of door or window separately.2) Make sure the inverted-V line of 2 parts are aligned, make sure distance between them should be less than 0.39in (1cm)4 Working Modes:1) General Alarm: Alarm goes off if door is opened, alarm sound will stop if door is closed. How to set: Toggle switch up. Prompt sound is "Di-Di"2) Constant Alarm: Constant alarm even door closed. How to set: Toggle switch up, down, up. Prompt sound is "Di......"3) Closing Door Alert: Sound "Di..Di..Di.." when door is opened, it will stop when door is opened. How to set: Toggle switch up, down, up, down, up. Prompt sound is "Di-Di-Di"4) Doorbell: Sound "DingDong" if door opens. How to set: Toggle switch up, down, up, down, up, down, up. Prompt sound is "DingDong"