We gear up for long days on the trail with the Rim Runner X20 70oz Hydration Backpack, which comes with a 2. 5L reservoir and plenty of packing space for the hiking necessities. The women-specific 3D Vent Mesh Harness creates a breathable and movement-friendly fit for comfort over the long haul, and a combination of zippered and drop-in pocket space keeps the small essential organized.