Abstract: A ventilation unit intended to serve as a supply and/or exhaust unit integrated into an air duct system in a ventilation plant, includes at least two tube sections connectable with a common axis with mutually adapted dimensions, whereby at least one tube section constitutes a fixed part of the air duct system, at least one tube section is displaceable relative to at least one axially connected tube section, two tube sections connectable along their axis are mutually displaceable and form an overlap area at their connecting end parts, at least one of these tube sections has one or several openings in the tube wall at and/or next to the overlap area, and the flow of air through the openings that can be opened, can be regulated with respect to its magnitude and/or direction through displacement and/or rotation of the two mutually displaceable tube sections.