We purchased the backpack for our daughter who recently fractured her spine. We noticed she was bringing home multiple books daily. The weight of her previous backpack with books was averaging 19-20 pounds. Adding that weight to a lower back fracture was riduclus. We checked several local retail stores and sporting good stores and were unable to find a satisfactory backpack that had wheels, wasn't overly clumpy and had the necessary space to store school books/supplies. Delivery from overstock was quick. The backpack arrived and she has been using for about two weeks now. This Calpak is, overall, very sturdy. The wheels have stayed in tacked even though our daughter is having to drudge through the snow and there is plenty of room for books. We've been pleased with results to this point.