DESC: Minimize the sweat! The Osprey Atmos 65 features an ultrabreathable backpanel and perforated foam padding in the hipbelt and shoulder straps that enhance cooling airflow. an ideal backpack for thru-hiking and week-long trips in warm weather. 4,000 cubic inch capacity. Extremely light weight. AirSpeed suspension makes the Atmos like no other ultralight pack 2 6005-T6 alloy aluminum with titanium struts provide flex in the middle with 3D contouring. All contact surfaces are either breathable mesh or perforated, molded waffle foam (no hot spots!). Tensioned, breathable mesh fabric provides superb airflow through back contact zone. Thermoformed and perforated waffle pattern harness and hip belt for further ventilation. Two hydration options: use the internal hydration sleeve or AirSpeed back panel for carrying your hydration reservoir (not included). Hydration tube ports on both right and left. Stretch mesh front and side pockets. Zippered hip belt pockets.