The handle member 120 is pivotally turnable about the second pivot section 122 to move between a closed position, as shown in FIG. 12, and a pulled-out position, as shown in FIG. 13. When the handle member 120 is in the closed position, the closing edge 121A is in contact with or located adjacent to the first partitioning wall 210; and when the handle member 120 is in the pulled-out position, the pulling-out edge 121B is in contact with or located adjacent to the first partitioning wall 210 and the abutting section 112 is pulled to move forward by a distance relative to the first partitioning wall 210.

According to the second embodiment, when the handle member 120 is in the closed position, it is located in parallel or non-perpendicular to the first partitioning wall 210; and when the handle member 120 is in the pulled-out position, it is located perpendicular or non-parallel to the first partitioning wall 210.