The arrangement has walls or parts of walls with plate-shaped base elements performing a screening function and which can have arms protruding into the housing. A lateral region extending perpendicularly with respect to the front wall of the base element has a groove which can be engaged by a U-shaped first arm of the spring element, which has a second arm extending along the lateral region. The first arm (42) of the spring element has a section with its forward region in contact with the side wall (24) near the front surface. The other arm (48) of the spring element is a U-shaped arm with an edge section (54) curved towards the first U-shaped arm.
