be pushed upward also the edge portions of the screen remain secure in the guide rails 14 even in case of very great wind forces fig8 is a diagrammatic view of the connection of a tube 23 with a pneumatic pump 24 which is mounted on the inside of the window to this end a lower elbow 24 39 is guided through molding 25 and guide rail 14 and inserted into the lower tube opening at 26 the pneumatic pressure pump 24 may have a diameter of a few centimeters so that it is not very noticeable the pump is pressed inwards by the thumb in order to introduce compressed air into tube 23 to clamp the screen 5 in order to release the air and raise the screen a push button check valve 31 is employed fig9 shows that a brush strip 27 is mounted in the area of the outer edge of the roller shutter casing in such a way that its resilient bristles rest on screen 5 so that during the upward and downward movement of screen 5 the bristles of the brush strip 27 sweep over the surface thereof and remove any adhering foreign particles the brush strip 27 constitutes an insect barrier as it reliably prevents insects which have passed into the roller shutter casing from getting into the interior of the room behind gauze 5 through the window or door opening moreover the brush strip 27 seals and insulates a considerable cross sectional part of the gap leading into the roller shutter casing the brush strip 27 is mounted on the front leading edge of a traverse member 28 which is flush with the front end face of the adjacent molding 29 the bristles of the.