Hydration backpack kit: this hydration backpack includes a water bladder (2L) for healthy use. 4 hours to cool liquids: the front pocket of the bike bag is designed with a separate insulating layer to effectively cool water and drinks for 4 hours. The wide opening makes it easy to fill, clean, and dry the bladder while clipping, and the bracket makes it quick and easy to open and close without leaks. Waterproof hydration pack Splash: The hydration pack contains 1 insulated layer, 1 main pocket, 1 front pocket, 1 front mesh pocket and 2 side pockets. SBS zippers are made of splash-proof nylon to keep water out and ensure long-lasting durability. It is ideal for hiking, running, cycling, camping, climbing, walking, hunting, riding, jogging and other outdoor activities. Comfortable Hiking Backpack: This cycling backpack features ergonomic S-shaped shoulder straps, double padded and adjustable, and a breathable waistband padded with mesh material tailored to your back, ensuring optimal comfort and all-day fun, even when fully charged. Improved reflective straps - including hydration pocket, which can be replaced with another bladder design. The hydration bladder is your faithful companion for cycling or outdoor sports. The reflective tape makes nighttime activities safer, it also increases the visible area and warns passers-by, making you safer and less likely to be injured after dark.