Hi! I am the SJ Gang MULTICOLOR GIRL 3WD- Wheeled Backpack, equipped with a 3-wheels system that helps you to climb of the stairs. Colorful and multipurpose, in a few simple moves from a trolley to a backpack and vice versa. My trolley has a reinforced bottom and corner protections to give stability to the wheeled backpack and protection to the contents. If you unhook the trolley, I become a washable backpack, super roomy, with a front pocket and comfortable to wear thanks to the padded back and shoulder straps. This latter, the shoulder straps, can be retractable when you use me as a trolley, or, thanks to the CROSSOVER SYSTEM, can automatically lifted up by pulling up the resistant double telescopic bar with two height adjustments, in order to not slide the belts on the ground.