Features: 1.120DB: Security door alarm with 120DB to detects entry, prevent kids and babies going out the house, protecting your home or office safety. 2.Low Voltage Warning: You will easily know when to replace the batteries with door alarm's low battery indicator, no worry about failing to work. 3.Simple Installation: Ultra slim door and window alarm, can be easily installed on any door or window, which will not damage your furnitures. 4.High Accuracy: Door bell alarm is suitable for sleeping alone children, the elderly and pregnant women, with high accuracy, and never false alarm. 5.Easy Use: When opening the door, the main machine will make a alarm sound of 120DB. When the door is closed, the alarm sound will stop. Specification: Item Type: Door Window Alarm_x000D_ Material: ABS_x000D_ Single Sensor Battery: 3 x LR44 Button Batteries 150mah (Included)_x000D_ Alarm Volume: 120DB_x000D_ Voltage: 4.5V_x000D_ Current: 60mA PackageList: 4 x Sets of_x000D_ _x000D_ Door Alarm 1 x Instruction