Mountain bikers and hikers both crave the flexibility of the BlowFish. With it’s expandable pocket open, this system becomes a 3-season pack. Zip it down, and it’s a super stable, low-profile summer system. Features: Redesigned Air Director back panel with Air Mesh harness enhances ventilation Expandable storage compartment gives you greater flexibility Secure cargo pocket includes internal organizer Include Slider Sternum strap and removable waistbelt Strap management secures loose webbing BlowFish Specs: Capacity (fluid): 100 oz / 3 L Cargo Capacity (Normal): 482 cu. in. / 7.9 L Cargo Capacity (Expanded): 781 cu. in. / 12.8 L Weight Filled: 8.36 lbs / 3.79 kg Weight Empty: 1.76 lbs / .80 kg Dimensions (Normal): 18’ x 8’ x 4’ / 457 x 203 x 101 mm Dimensions (Expanded): 18’ x 8’ x 8’ / 457 x 203 x 203 mm