The secured ventilation function of the window sash is ensured in the adjustable end position by magnetic force. As soon as the specific components come into contact / touch each other in the selected end position of the opening position, the window is held in position by the adhesive force of the magnets. The function can be adapted to the requirements of different window sizes and weights by selecting different magnets with different holding forces. By positioning the magnetic component in the sash frame, the end position and thus the opening width of the window can be set or adjusted according to the existing requirements.