Please refer to FIGS. 6, 7 and 8. In the first variation of the first embodiment, the flanged bosses 113A, 113B respectively have a body portion 1131 and a flange portion 1132 formed around a free end of the body portion 1131. The quick-release guide rails 212A, 212B respectively have a rail portion 2121 and a quick-release hole portion 2122 communicable with the rail portion 2121. The body portions 1131 of the flanged bosses 113A, 113B are separately movably received in the corresponding rail portions 2121. The flange portions 1132 of the flanged bosses 113A, 113B have a diameter larger than a diameter of the body portions 1131 and a width of the rail portions 2121, so that the flanged bosses 113A, 113B are limited to move only within the corresponding rail portions 2121. Also, the diameter of the flange portions 1132 is smaller than a diameter of the quick-release hole portions 2122. When the flanged bosses 113A, 113B are moved in the rail portions 2121 to positions corresponding to the quick-release hole portions 2122, the flange portions 1132 can be moved out of the quick-release hole portions 2122, allowing the pull-out aiding device 100 to be detached from the first partitioning wall 210.