Thank you for providing your feedback on the Rubbermaid #2463 Roughneck Wheeled Storage Box.
The lids on this container are beveled, making stacking difficult as the containers will "wobble" on top of each other. Also, the weight of a stacked container would not be evenly distributed and could damage the storage box. The majority of the weight of the stacked box will rest on the highest point of the lid below it and could cause the lid to crack.
The containers, when empty, can be nested inside one another for easy storage.