At both ends of a filter cover (6), respectively in the fastening area of the filter cover on draining element (1), bondings or settings (12, 14, 15, 16, 17, 18, 19, 10, 21) of stitches (10) are applied, which are interrupted in one or more of first rows of stitches (11) and are offset in one or more rows of stitches at the end of the fastening area in the peripheral direction. In a modification, setting (22) of stitches (10) at the end of the fastening area is placed uninterrupted in the peripheral direction. These settings partially or completely allow runs in the fastening area of a filter cover (6), so that, on the one hand, an enlargement of filter cover (6) is made possible for the assembly, and, on the other hand, the formation of runs outside the fastening area is prevented.