Sturdy enough to hold lots of hardcover books small enough to not get too heavy. Lots of space for describing contents. Assembles easily and folds compactly for repeated uses.
I bought two sets of these boxes to help move and store my classroom materials when I was pink slipped in my district. The boxes were easy to assemble (6th graders were able to put them together) and sturdy enough to hold my volumes of books and binders. The lids are useful for stacking the boxes. A great buy!