【25 Liters Super Capacity】The 2L lightweight hydration pack backpack can hold up to 25 liters of items and gear, 17.7*5.1*7.8 inches compact body but with a large capacity. The multifunctional pockets of the hydration backpack allow you to carry your outdoor items as needed, but it won't feel heavy. Because the water bag backpack is only 15 oz. The backpack has three main compartments for towels, clothing, food items, two side mesh pocket openings for water bottles umbrellas, and additional small pocket openings for money jewelry, etc. 【INSULATION】 Insulation material compartment is made of tin foil, assembled with a 2-liter TPU water bladder, the insulation pockets can be used to place wet towels ice packs to keep cold, the thermal insulation effect can be as long as 4-6 hours to keep the outdoor sports can be physically cooled down. The tin foil material can be easily cleaned and will not penetrate. 【High Flow Bite Valve】 The 2L TPU bladder is double heat-press sealed, leak-proof and explosion-proof, BPA-free food-grade material, 17*39cm water bag comes with 100cm length of water guide tube, 5cm water inlet for water filling and ice cooling. Manual on/off valve helps prevent leakage, food-grade spout bite valve allows easy high-flow water flow for easy drinking, drinking to your heart's content is the greatest fun in the outdoors. Abrasion resistance, flexing and hydrolysis are the advantages of TPU water bladder. 【Soft and Breathable】The lightweight water bladder is made of lightweight and breathable mesh fabric, 3D breathable padding on the backrest improves breathability, soft backrest prevents skin friction during exercise, elastic chest strap with safety whistle and adjustable to the right position shoulder straps fit better to the back during exercise, reducing bouncing and weight bearing during cycling, running, hiking and mountaineering exercises.