The largest model in the Stratos Series, the Osprey Stratos 36 is a medium-size backpack that's designed for day hiking as it focuses on ventilation. The backpack features a 3D tensioned mesh backpanel with side ventilation and has bungee webbing for hydration routing. It also includes stretch mesh back panel and LightWire alloy frame for a comfortable and custom fit that tailors to an individual's body. With two side mesh woven pockets and zippered hipbelt pockets, the advanced hiking backpack has an integrated raincover to protect it from different weather conditions.