Perfect FitThis running vest is ergonomically and contoured to fit the body perfectly, the adjustable waist and chest straps can adjust the size according to your body type, preventing annoying bounce and shaking while running.Super ComfortableStretch mesh fabric brings cool comfort to your back, and the light and soft shoulder straps will not rub against the skin at all.Ultra Lightweight DesignHigh-quality nylon material and ultra-lightweight design, more comfortable to exercise,sports backpack only weighs 300 grams, 12(H) x 2(W) x 8(L) inches ,the main compartment can hold 3 liters, the left and right shoulders have pockets for storing 250 ml PET bottles, and There's a pocket for your phone and stuff, and you can jog while listening to music.Premium Water Bag1.5L/2L food grade water bag which can quickly fill with water and ice, while making it easier to clean the water tube (40" long, 0.4" diameter) Provides healthy water flow for easy drinking, water temperature The range is -20~+50.Safety MeasuresThis running bag is equipped with a safety whistle, and multiple reflective designs increase the safety in dark conditions. The practicalbackpack is designed to accompany you on your trips like marathon, jogging, trail running and more. It is suitable for men, women.