The back system is filled with AirMesh for greater comfort when carrying the backpack. It has adjustable shoulder straps, a chest strap and a waist belt. There are two mesh pockets on the sides and a zip pocket in the front, which also has a mesh pocket for better organization of personal items. Inside the backpack there is a zip pocket at the lid level. The inside of the backpack is impermeable. So you don't have to worry about food or drinks leaking. When condensation forms, water remains at the bottom of the backpack. If you want to keep food or drinks cold for longer, we recommend adding cooling pads. Without them, the backpack will keep drinks and food cold for 6 hours.