The sensor will see through wood, plastics, glass, textile and literally anything without metal. The denser the object, the more the detection range will be reduced, so don’t expect wonders. It cannot look through an entire building, but sheets of plaster and normal walls is no problem.

The one thing that really disturbs the sensor is metal. Be sure to place the sensor with a free line of sight to the area you want to detect. With “free line of sight”, we basically mean “without any metal objects in the path”. If there are any metal objects in the detection zone, they will create “dead spots”.