The Gregory Arrio 28 L Backpack is a lightweight pack for long day hikes. Spacious but not too big, the 28 liters offers space for layers, emergency rations, and even the hammock. A VaporSpan tensioned backpanel allows air to flow, keeping you cool as the exertion intensifies. A sternum strap and CloudControl hipbelt prevent the pack from swaying, without deterring your natural movements. This pack is hydration compatible, but the reservoir is not included.