Product details:

The truly innovative Sierra Designs Flex Capacitor 40-60 backpack has an integrated, gusseted compression system that lets it swiftly expand from a 40 liter to a 60-liter capacity. In spite of its lightweight design, it's still capable of carrying heavy loads. Balancing weight and performance, the pack utilizes a Y-shaped DAC aluminum suspension system to ensure vertical rigidity while allowing the top portion of the pack to flex with your movement. The result is maintained load stability without excessive bulk or weight. Raised padding in the lumbar and scapula regions of the backpanel provide support and cushioning while also creating space for airflow. A padded and adjustable hipbelt further enhances balance while load lifter straps and a sliding sternum strap allow you to dial in fit. The pack is available in Small/Medium (best fits 16'-19' torso lengths) and Medium/Large (18'-21') sizes to make certain that the wearer best benefits from the structural design of the pack. The top-loading pack employs a U-shaped zipper to offer wide-open access to its interior. By adjusting the horizontal compression system that runs across the face of the pack, you can utilize the full 60-liter capacity or cinch down to secure contents and 'shrink' the pack to a more streamlined 40 liters. A stash pocket on the lid, stretch mesh side pockets, and two large hipbelt pockets provide additional storage and organizational options. Other features include front harness pockets that are perfectly sized for a water bottle (bottle not included), ice axe/trekking poles loops, and an internal hydration sleeve (hydration system not included) that can be removed if not needed or if you simply want to shave ounces. The Sierra Designs Flex Capacitor 40-60 internal frame pack is available in your choice of colors and sizes.Nylon material makes the backpack resilient for prolonged use
The Y-flex suspension system helps reduce the strain on your back while carrying
Designed with adjustable straps to manage the backpack capacity