Xiaomi Mi Door and Window Sensor 2 Manual De Usuario página 6

Installation
1. Apply the adhesive stickers inside the bo om grooves of the sensor and
the magnet respectively. Tear off the protective film from the adhesive
stickers when installing.
2. Align the marks on the side of the sensor unit and the side of the magnet
as much as possible during installation.
Try to align the installation marks.
5