Description: Proper Fit: This Trail Running Backpack is ergonomically designed to perfectly fit your body. The adjustable waist and chest straps can be tailored to your body shape, preventing annoying bouncing and swaying while running.Comfortable Material: The elastic mesh polyester material of the running hydration vest provides a cool and comfortable experience for your back, while the lightweight and soft shoulder straps are comfortable to wear.Large Capacity: This running hydration vest backpack has a main compartment that can hold up to 3 liters, pockets on each shoulder that can store 250ml bottles, and a pocket for your phone so you can listen to music while jogging. In size 38cmx20cmx10cm/14.96inchx7.87inchx3.94inch.Quality Hydration Bladders: The running hydration vest comes with two 250ml and 1 1.5L hydration bladders that can be quickly filled with water or ice for drinking. The water temperature range is -20~+40 degreesWide Applications: This running backpack is equipped with multiple reflective designs to enhance in dark environments. It's suitable for activities like marathons, jogging, trail running, and more; great for both men and women. Specification: Material: Polyester Size Chart: 38cmx20cmx10cm/14.96inchx7.87inchx3.94inch Package Includes: 1 Backpack 2 250ML Soft Water Bottles 1 1.5L Water Bladder Note: Please allow slightly errors 1-2cm differences due to manual measurement.