The Large #4500, which can accommodate most larger laptop computers, is designed to carry the heaviest load in our product assortment and fits larger frame students of all ages who are 5' 5" or taller or whose body measures 17" or more from the top of the shoulder to the natural waist. Physicians recommend that students carry no more than 15% of their body weight on their shoulders and backs, yet studies show younger students are lugging as much as 40% each day. Smart design features include: patented lumbar air cushion and wider shoulder straps adjustable both top and bottom that automatically adjust side-to-side to help maintain correct ergonomic support; two large interior compartment for heavier books and other necessities, side cinch straps to secure extra load closer to the back, a large front pocket with organizer for notebooks, pens and pencils (even a handy key keeper, CD player pocket and headphone ports), a front zipper pocket, padded haul handle, one side mesh bottle pocket, one side fabric pocket with buckle and a new detachable cell phone/mp3 holder. Made of durable Poly Oxford 600D material. Comes in a variety of popular colors. Dimensions: 18" x 12.5" x 12". Capacity: 2600 cubic inches. Mini air pump included.

Physicians recommend that students carry no more than 15% of their body weight on their shoulders and backs, yet studies show they are lugging as much as 40% each day. Recommended by the Congress of Chiropractic State Associations and developed with orthopedic professionals, the unique AirPack System, has been university tested and clinically proven to help students tote today's loads more safely and comfortably. Our patented, ergonomic air-transfer system, with its inflatable lumbar cushion and wide shoulder straps, redistributes weight from the shoulders to the hips and lower back to promote an upright standing position and enhance the body's natural ability to carry weight. Smart design features include: shoulder straps that automatically adjust side-to-side to help maintain correct ergonomic support, even when using just one strap; adjustable strapping for even more customized fit, three convenient zipper compartments that help organize books, pens, and other necessities (even a handy key keeper), and two mesh bottle pockets. Made of durable polyester in a variety of popular colors. 18.5" x 12" x 10.5". Capacity: 2600 cubic inches. Mini air pump included. The Large fits larger-sized middle or high school, college students and adults who are 5' 5" or taller or who measure 17" or more from the top of the shoulder to the natural waist (a shorter person 5' to 5' 5" or shorter torso 15" - 17" might consider the Medium). Measure first, get the right size and enjoy AirPacks relief soon.