Its a mount for a Sonoff motion sensor (SNZB-03). It allows to stick the mount to a wall, door, or something similar but still have to option to easily access the motion sensor to for example change the batterie or bring it with you if you work on a place where the motion sensor normally would not see you and therefor turn off the lights while you are still working there. The mount is designed to fit the motion sensor with its adhesive strips sticked on. If you use it without the adhesive strips you might need to scale it down a little bit, but I havent tested that way yet.