Granite Gear incorporated key elements of its award-winning Ozone pack to create the Nimbus Trace Backpack. In addition to more exterior storage and a removable top lid, the Nimbus Trace incorporates the 3D TopoFlex internal frame, which offers great freedom of movement along with a more precise fit and continuous support. Carrying a 50-pound load on a three-day backcountry jaunt never felt so good.