Part courier bag, daypack and carry-all, the Atom's teardrop shape provides the support of a daypack by positioning the load behind your shoulder. The single-strap design makes getting to the goods simple: Just spin it around front. The large zippered main pocket has zippered mesh and stretch-woven pockets inside to organize small items. A convenient zippered pocket on the shoulder strap has a soft lining to protect valuables. Breathable, 3-D spacer mesh pads the shoulder strap and back panel to wick moisture, dry quickly, and increase ventilation. For biking and hiking, a stow-away waistbelt keeps the pack close to your torso. Made of a 420-denier 100% nylon oxford plain weave, with an 840-denier 100% ballistics nylon bottom. The lining is 200-denier 100% polyester. All fabrics have a Deluge DWR (durable water repellent) finish.