Adjustable Shoulder/Chest/Waist strap, allows the hydration pack fit you comfortable. Lightweight and splash resistance enhance the practicality. Two chest pocket for your phone, keys and small items. Reflective tabs increases the hydration vest visibility in dark.The hydration backpack included 2 Liter hydration bladder for men women kids. The perfect size offer a nice balance of reasonable weight and bulk while providing a sufficient quantity of water, fit for hiking, running, biking, climbing.