The boxes are designed for installation under parget and subsequent assembly of the instruments. The boxes have flexible inlets, which ensure the airtightness of the installation and are therefore suitable for low-energy and passive buildings as they reduce heat loss of the building. The unique shape of the box ensures a large interior space for installation. The boxes can be connected for the installation of instruments in the multiple frames, while the newly designed connection is very rigid and thus ensures accurate installation in the wall. They are available in two sizes with depths of 45 and 70 mm.