The Small #3300 ergonomic backpack: is an ideal AirPack Backpack for a smaller elementary school student. It’s also perfect for a petite middle or high school student or adult who is shorter than 5' 0".
The Medium #4300 ergonomic backpack: is designed to fit any larger-sized elementary school student or average-sized middle school, high school and college student. It also fits an  adult who is 5' to 5'5" tall or whose body measures between 15" and 17" from the top of the shoulder to the natural waist.

The Large #4500 ergonomic Backpack: is good for your laptop, too. The backpack features a new built-in padded compartment that can accommodate a standard-sized laptop computer. The Large ergonomic backpack is designed to carry the heaviest load in our product assortment. It 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. .

Health Information:

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. The AirPack Backpack’s inflatable cushion helps reduce back stress by acting as a fulcrum to redistribute weight from the shoulders to the hips.
In addition to that patented lumbar air cushion, standard ergonomic design features include wider, foam cushioned shoulder straps, adjustable both top and bottom with unique slide strapping. The straps automatically adjust side-to-side to help maintain correct ergonomic support.

Additional features:

in the Medium ergonomic backpack include: padded haul handle, built-in padded laptop compartment, a large interior compartment for heavier books and other necessities, a large front pocket with organizer for notebooks, pens and pencils (even a handy key keeper, CD player pocket and headphone port), a front zipper pocket, and a new detachable cell phone/MP3 holder.  

Made of durable Poly Oxford 600-denier material.  Available in a variety of popular colors.  Dimensions: 17" x 11.5" x 8" (43cm x 29cm x 20cm). Capacity: 2000 cubic inches. Mini air pump included.

Care Instructions:

Hand wash with mild soap or wipe with damp wash cloth.  Air dry. Machine wash and dry is not recommended.

Guarantee:

AirPacks Backpacks are included under our satisfaction guarantee. We will be happy to replace backpacks that do not meet our standards of quality and performance. Our warranty does not apply to damages caused by typical wear and tear over time, unreasonable use, accidents or neglect.  If you have questions regarding your backpack or the warranty, please call hemingwaymassageproducts at (866) 865-4988 or email at orders@hemingwaymassageproducts.com