Installation and Pairing: You can control this sensor remotely through the app or by voice using Alexa or Assistant to warn intruders away and alert the owner. (Need to bring your own battery) There is a super sticky adhesive on the back, which is and not easy to fall off, avoiding screw holes in doors and , super adaptable and stable. : sense the number of doors and opening and closing, allowing you to monitor the opening and closing of doors and anytime, anywhere. When you forget to close the door, your smartphone will notify you immediately without delay, preventing thieves from entering the room. [Record Export] Display the detection status of the last 30 days Safe and reliable: the product is strictly made of plastic abs material, which is not easy to damage (note: the sensor has no alarm system, and will only push data to the APP in real time) Power Suplly:2 x AAA batteries(Not included batteries) Colour:White Material:ABS Package Contents: 2 pairs * magnetic door sensors 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.