The smart sensor is used to determine the opening or closing state of a window or door (closet, refrigerator, mailbox, ...) and is part of the Tapo smart home family. Powered by a small CR2023 long life battery, this sensor communicates wireless frequency 868/922 MHz with the control panel which is necessary for the sensor to work. For simple tool-free installation on any flat surface, double-sided 3M adhesive tape is used on the back of the sensor.