Osprey's Atmos 65 Backpack has become the no-brainer pack of choice for warm-weather backpacking. The AirSpeed back panel is designed to circulate more air to keep you cool on exposed trails and warm, humid mountain treks; it features a LightWire alloy peripheral frame that creates a low-profile airspace while optimizing balance, as well as scalloped side openings that enhance cross-ventilation. Throw in a highly customizable fit, incredible light weight, and a host of pockets and features, and you get a pack that's ready for anything in any season.