The Osprey Aether 70 is the mid-range model in the lightweight Aether series of men's mountaineering backpacks. Available in three colors and three sizes, the 2010 Aether 70 introduces several new features. The top pocket can be removed and converted into a lumbar pack, and built-in cord loops allow certain Osprey daypacks to be attached. Other key features include an internal compression strap, removable sleeping pad straps, and hydration system support for reservoirs up to 3 liters. The Ariel Series offers the same features but is designed for women.