MOUNTAINTOP Hiking Hydration Pack Backpack Cycling Running Bicycle Walking Climbing Camping Biking Bag MATERIAL- Polyester ,Water-resistant Polyester as the fabric do not allow water to easily penetrate.RAIN COVER included. CAPACITY- 13L (793 cube inches); High quality hydration pack for cycling, hiking and climbing, designed to be comfortable and functionally versatile. BEARING SYSTEM- Breathable mesh shoulder straps and mesh back panel.Keep your back and shoulders cool and comfortable. MULTIPLE FEATURE- Reflective strip design, higher safety factor for night; more humane, more convenient for travelling. HYDRATION SYSTEM COMPATIBLE- Internal hydration bladders compartment and water tube outlet (bladder not included).