along the guide rails 3 4 a winding shaft 9 designed as a hollow shaft is provided for winding up the first shading means 6 the winding shaft 9 can be held on a drive shaft 11 with the interconnection of a torsion spring 10 the drive shaft 11 is provided with two first toothed belt pulleys 12 a 12 b which are essentially fitted at the ends the first toothed belt pulleys 12 a 12 b are connected via first toothed belts 13 a 13 b to second toothed belt pulleys 14 a 14 b which are provided in the vicinity of second ends e 2 of the guide rails 3 4 the designation 15 refers to a first electric motor which can optionally be connected in terms of drive via a first coupling 16 at least to the second toothed belt pulley 14 a a first displacement bar 17 is fixedly connected in each case to a rear strand of the revolving first toothed belts 13 a 13 b at both of its ends the first displacement bar 17 is designed in such a manner that it is guided slideably in the guide rails 3 4 a first guide means 18 can be provided at at least one of the two ends of the displacement bar 17 fig4 5 and 7 show perspective views of the device as per fig2 and 3 with the essential components of a second shading device additionally being shown here as is apparent in particular from fig7 the second shading means 7 is a pliss u00e9 folded in the manner of an accordion the second shading means 7 is attached by an edge to a second displacement bar 19 which is likewise guided slideably in the guide rails 3 4 for.