1.[Latest Ergonomic Design]Our backpack is designed with the latest ergonomic design, taking into account the adjustability and body fit to ensure that it fits the needs of users of different sizes, while minimizing the bouncing and shaking during the running exercise, providing you with a comfortable using experience. The specially designed breathable mesh cover ensures air circulation on the back, keeping you cool and preventing discomfort due to heat buildup, while providing good ventilation. 2.[ULTRA LIGHTWEIGHT & PORTABLE DESIGN] Choose high quality nylon material and ultra lightweight design to make driving more comfortable. Our sports backpack weighs only 140 grams, 14.5 (H) x 7.8 (L) x 2 (W) inches, the lightweight design ensures comfort when exercising and ensures that even for long periods of time, it will not add extra load to the body 3.[Multi-storage design]While ensuring lightweight, our packs are set up with plenty of storage space The main compartment can hold 1.5~2 liters of water bladders. In addition, the left and right waistbelt pockets are specially designed to store 250ml PET bottles. There is also a zippered pocket next to the main backpack pocket for carrying small items such as a cell phone and key cards, so you can listen to music while jogging! 4.[Safety and Unique Design]1, The backpack is designed with multiple reflective trims to increase for use at night/dark environment. Strap clips keep extra straps secure.2, The outer backpack cord can tighten the backpack to minimize wobble or extra bundle other items such as riding helmets, etc., which is highly expandable.3 The backpack's outer water-resistant fabric prevents rainwater from getting in, even in inclement weather.