Abstract: The invention relates to a dust bag to be used primarily in vacuum cleaners, the dust bag having at least two opposing wall portions of filter material in an overlaying state and an intake opening for receiving a socket piece of a vacuum cleaner. The two opposing wall portions are connected to each other at one edge forming an outer edge of the dust bag. The wall portions each have recess open to the outer edge. The recesses (36a, 36b) are identical in their shape and size and opposed to each other in the overlaying state. The two recesses of the wall portions form the intake opening. Additionally, the intake opening can be surrounded by a mounting means for mounting the dust bag at a socket piece from which dust-like material is discharged. The mounting means includes at least two mounting elements each fixed to one of the two wall portions.

Abstract: The filter device (10), provided for the filtration of fluids, comprises two interconnected material structures (14,16) forming a filter unit (12). The two material structures (14,16) are mechanically stable, at least one of the two material structures (14,16) being elastically deformable. The two material structures (14,16) are connected to each other at opposite connecting sites, with one (16) of the material structures forming an arch between the connecting sites. This arch has been generated by elastic deformation of the respective material structure (16) so that this material structure (16) is mechanically biased. A stretching movement of this material structure (16) is prevented by the connection of this material structure (16) to the other material structure (14) which in turn is of substantially plane configuration and is tensioned.