Descriptions: Principle of operation open/close prompt: when someone opens the door or window (door magnet host and magnetic stripe separation) immediately sends out an alarm sound and pushes the SMS to the cell phone to prompt the door to be opened/closed Doorbell mode: when you are , turn on the doorbell mode as a reminder of visitors, when you go out, set the alarm mode to guard your home. siren size: 5.7 x 5.7 x 1.6cm magnetic strip size: 5.7 x 1.5 x 1.6cm Material: ABS colour: white Package Contents: 1 x siren 1 x magnetic strip 2 x AAA batteries 1 x sticker Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. The app will also alert you when the battery is low Alarm mode: when the door is opened abnormally, the door magnet immediately emits 80dB alarm sound and pushes the information to the cell phone. Doorbell mode: when you are , turn on the doorbell mode as a reminder of visitors Open Graffiti/Smart Life APP to check the opening and closing records of the door magnet, and keep track of everything in your home. No need to worry about whether you forget to close the and doors when you go out, you can easily check the status of and doors through the interface of Graffiti/Smart Life APP, so that you can travel without worry.