This is how it works: The door and window chime alarm sensor sends notifications to your phone (via a smart life app, a message or a call) when the door or window is open. It is no longer possible to confuse whether the door is closed with the alarm door sensor. Reliable security for the home: When you detect forced entry, the door security alarm will send you a notification within 8 seconds, so you can take some immediate steps to protect your family. When children sneak out, the wireless security alarm will let you know that this is just a perfect smart security alarm for child safety, anti-theft, home, garage, mailbox and business security. Smart Lifestyle: The door window sensor is compatible with Alexa Google Home, smart car turn on light accessories. Just use the sensor as a trigger, set up the gate opening to make an announcement on one of your Alexas and let the lights come on. Easy installation: The package includes the kit required for easy installation. Just take a few minutes to complete the process and make sure the sensor and magnet are aligned and less than 10mm apart. Warm tips: The window alarm requires 2 AAA batteries (NOT included), working at 2.4GHz, no built-in siren but the alert message to your phone.