Smart door and window protection alarm triggers immediately when the door is opened. Password disarming function requires entering the correct password to disable the alarm, ensuring security and preventing unauthorized manual disarming. Working principle of the door sensor alarm: After arming, if the distance between the alarm unit and the magnet exceeds 1.5cm, the alarm will sound and send an alert to your mobile phone and computer. Power Supply: 2 x AAA batteries (batteries not included) Color: White Material: Plastic Package Contents: 1 x Smart Door Window Alarm Sensor Kit Note: The package includes only the items listed above; other items are not included. Note: Light reflection and differences in display screens may cause slight variations in the color of the item as shown. Measurement error allowance: +/- 1-3 cm.