FUNCTIONAL HYDRATION: One Size Fits All - Hypernight QuickStart 2.0 4 Liter Hydration Pack gives you the best of both worlds. Equipped with a 1.5L bladder, 2 easily accessible front pockets, and extra storage, you'll be ready to hit the trails for a hike or some walking ESSENTIAL DESIGN: Made of moisture wicking stretch woven fabric & chafe free binding materials for maximum comfort plus, breathable mesh shoulder straps. Front storage for nutrition and phone fits most large format smartphones, front bottle pocket fits up to 22oz flasks, and main back zipper pocket. SIZING & FIT: One size fits most. Adjustable front and side straps for a perfect fit SPECS: Weight without bladder: 7oz; Weight with bladder: 12oz; Storage capacity: 4 Liters (44 cu in). INSPIRED BY THE JOURNEY: Nathan's collection of running essentials delivers on what matters most through intuitive design, comfort, quality, and smart storage, to help runners enhance and improve their performance, mile after mile and year after year