The items were a preselected set of

The items were a preselected set of 25 products commonly
sold on Amazon.com which would pose varying degrees of
difficulty for the contestants’ robots. The full set of items is
shown in Figure 2. Simple cuboids, like a box of coffee stirrers
or a whiteboard eraser, were among the easier items to pick.
Larger items such as a box of Cheez-Its posed a challenge
because it could not be removed from the bin without first
tilting it. Smaller items, such as an individual spark plug,
were more difficult to detect and properly grasp. The range of
cuboid sizes was intentionally chosen to challenge traditional
fixed-throw gripper designs that can operate only in a narrow
range of possible object widths.