Door and Window Contact Sensor: This magnetic door and window alarm will sound a 130 dB volume buzzer when the door is opened. It can prevent your children from sneaking out. And it is a perfect anti-theft wireless security magnetic alarm for child safety, home safety, garage safety, mailbox safety and business security 4 alarm modes : It has 4 alarm modes: 1 Ordinary alarm mode (the alarm will sound for 1 minute if the door is opened); 2 Wireless doorbell mode (“Ding dong”, sounds once as a welcome tone); 3 Alarm and Stop Mode (sounds loudly if the door is opened, and it will stop as soon as your door is closed); 4 Door close reminder mode (“Di Di”), from bottom to top, it will remind you with a repeated sound until the door is closed) Easy to install: This Security kit with alarm for home/window comes with self-adhesive pads, so no tools are needed, just stick the sensor and alarm to the door or window. It can also be used as a door stop alarm, swimming pool door alarm, garage door alarm or sliding door alarm Automatic and quick switch: With an ultra-sensitive magnetic sensor, this Alarm kit can quickly detect if your door or window are open. Powered by 2 AAA batteries (not included) Number of shipments: 2 pieces (without battery)