It's no surprise that the Osprey Exos 46 won Outside Magazine's Gear of the Year award for 2009. The Exos series packs focus on being ultra-light weight, without compromising comfort and necessary features. There are 3 packs within the Exos series (34,46,58 -- the numbers are based on capacity in Litters of the Size Medium Pack), and three sizes of packs within each style. Due to my size and the capacity I needed, I selected the Exos 46, size Large. It weights just 2 pounds and 7 ounces, and has 3000 cubic inches of cargo space. Osprey recommends a carrying weight less than 35 pounds.