Features & Details Practical & Innovative Water Bladder: This hydration backpack has a large opening for effortless filling and cleaning. It features an automatic shut-on/off valve to avoid leakage, a 360° mouthpiece with a dust-proof cap to maintain hygiene, an ergonomic handle design for convenience and functionality. Experience a seamless and convenient drinking experience. 2L Practical Water Bladder: The hiking backpack with water bladder includes a food-grade TPU water bladder, ensuring a pleasant drinking experience. Its leak-proof automatic shut-on/off valve and sealed detection technology avoid leak risks, providing you with peace of mind. Durable & Waterproof Polyester: The running backpack is made from waterproof polyester material. It is tear-resistant and abrasion-resistant for various outdoor conditions. The brand zippers are tested 3000 times for long-lasting durability. Experience smooth and effortless use on adventures and long trips. Your Ideal Storage Companion: The hydration pack backpack boasts a 25L large-capacity design. In addition to the main pocket for a 2L water bag, the large-capacity main pocket can also store clothes and tablets, multiple inner pockets hold wallets, phones, food and other items, while the outer layer features elastic storage cord for attaching hiking poles, shoes, clothes, towels and other gear. Flexible and customizable storage keeps every item within reach. Security and Functionality Outdoors: This hiking hydro backpack offers breathable mesh back padding to reduce stuffiness, and shoulder and waist straps with foam padding fit securely, providing a comfortable all-day carrying experience. Water tube clips and an emergency whistle enhance security performance, making it suitable for cycling, long-distance hiking, outdoor traveling, mountaineering and other multi-scenario needs.