【Hydration Vest Backapack】Running vest fit for 2L water bag (not included,) for quick hydration during running, suitable for medium and long distance sports. 【Material and Design】Running vest is made of polyester, lightweight, durable, and comfortable to wear. 【Multiple Storage Compartment】Designed with 10 front pack pockets, you can store items such as water cup, key, phone, cash, etc., and bladder or other items can be held in the back. 【Feature】Ergonomic designed vest bag comes with an adjustable chest strap that guarantees the perfect fit, keeping the pack from bouncing while running. 【Applications】This backpack is not just for running and hiking. but also suitable for outdoor activities, such as cycling, mountaineering, climbing, marathons, etc. Specification: Material: Polyester Size Chart: S: Length 44cm/17.32inch, Bust 78.5cm/30.91inch (chest circumference 78cm-86cm/30.71inch-33.86inch) M: Length 45.5cm/17.91inch, Bust 83.5cm/32.87inch (chest circumference 87cm-92cm/34.25inch-36.22inch) L: Length 47cm/18.50inch, Bust 88.5cm/34.84inch (chest circumference 93cm-99cm/36.61inch-38.98inch) XL: Length 49cm/19.29inch, Bust 93.5cm/36.81inch (chest circumference 100cm-107cm/39.37inch-42.13inch) XXL: Length 51cm/20.08inch, Bust 98.5cm/38.78inch (chest circumference 108cm-120cm/42.52inch-47.24inch) Package Includes: 1 Hydration Vest Note: Please allow slightly errors due to manual measurement and different monitors.