Door & Window Open Alarm: This SECRUI magnetic door window alarm sensor will emit a high volume alarm of 120dB when the door is suddenly open. It can prevent your kids from sneaking out. And it’s a perfect door alarm for kids' safety, anti-theft, home, and business‘ security..4 Alarm Modes: It has 4 types of alarm modes--#1 Ordinary alarm mode (Alarm will last for 1 minute if your door is being open); #2 Doorbell mode (“Ding dong”, rings once as a welcome tone );#3 Alarm and Stop mode (It will alarm loudly if the door is open, and it will stop as soon as your door is closed);#4 Door closing reminder mode ("Di Di", from low to high, it will remind you by repeated sound until the door is closed)..Easy to Install: This security kit can be easily installed as it is adhesive on the bottom. You just need to stick the alarm sensor on the window or door, then the installation is finished. It can also be used as a doorstop alarm, pool door alarm, garage door alarm or sliding door alarm..Fast Automatic Switch:Ultra-sensitive magnetic sensor can quickly detect your door or window status, The wireless door alarm sensor works with 2*AAA battery (batteries are not included)..No Worry Purchase: Each SECRUI customer is valuable and will be supported by 7 days*24 hours online service. We also offer a 12-month warranty. Please contact us for a satisfactory solution if any trouble happens to you.