BackTpack 4 Ergonomic Backpack, School Bag, Laptop Case, Black/Khaki One size fits adults and children from 4 feet and up. Highly adjustable to accommodate different body types and body sizes. Narrow back panel creates a contour of shoulder straps for comfort, sizing, and stability on shoulders Ample bag capacity to accommodate ipads and laptops, with a total of 12 compartments, including exterior water bottle holder on right side, cell phone pocket on left, and headphone/tube port on each side Locking system for hip width, allows adjustment for narrower or wider hips, and holds the weight of the bags when leaning forward as in bicycling Hip-loading belt is an integral part of the bag, for the option of transferring load off of spine to hips.