HIKA 25L Ultra Light Weight Outdoor Sports Hiking Backpack Cyling Daypack with 2L TPU Hydration Bladder DURABLE:Made of water resistant rip-stop nylon Reforced SBS zippers of high quality; Hydration sleeve to carry your water bag Equipped with outlet pipe and a pipe clip. (include a water bladder) Suspension back panel with mesh panel for ventilation airflow and superior comfort A whistle on the chest strap and the light reflection strip design which can produce the strong reflected light ray to perform the warning function to ensure your safety Compression straps are designed to cinch down and secure gear while carrying. These straps are also ideal for providing extra storage for items like jackets and sleeping bags