The back system in the Lowe Alpine AirZone Centro 4510 Pack minimizes the contact your back has with this overnight pack. This enhances airflow so you stay cooler and drier on backpacking trips. Pack gear for one or two nights in the AirZone Centro 45, adjust the torso length, and hit the trail. Side zippers make it easy to find an extra layer when the weather gets chilly, and the large expandable front pocket holds snacks and maps. The AirZone Centro Packs extendable lid makes space for an extra 600 cubic inches of gear for longer trips.