100% NylonThoughtful Storage Details: Running backpack bidirectional main zipper pocket for a water bladder, small storage compartments on front, two small mesh pouches for umbrella, mineral water, BlueTooth stereo, two mesh pouches on the shoulder on phone, and keysComfortable & Breathable & Adjustable: Multi-adjustable shoulder straps on hydration Pack, adjustable to 19"-34" on should straps, 2.4"-7.9"on chest strap(up & down). Hydration packs are suitable for adults. Ergonomically fits for your shoulders, chest, and waist. Soft air mesh back speeds up the air flow and makes your back coolAfter sale: If you have any problems, please reach out to us, we will reply within 24hrs. (We provide replacement services for quality problems within 1 year and lifetime customer service)Lightweight 12 L Hydration Backpack: Super lightweight 8.5 oz hydration pack backpack with 2 L water bladder. Waterproof and tear-resistant fabric, PU coated nylon hydration pack bears 25 lbsImportedLeakproof & Anti-popping Water Bladder: Water backpack for hiking with 2 L bladder, BPA-free, food-grade PEVA material, and hose clamp. Leakproof bite value, water flows fast and never drips on when lockedMultiple Use: Our hiking backpack with water bladder is suitable for hiking, running, MTB cycling, cycling, climbing, music carnival, and other occasions. This running hydration vest can be a are great companions for families and friends. focuses on outdoor sports backpacks, and vitality blooms from here