MOUNTAINTOP Hiking Hydration Pack Backpack for Cycling Running Bicycle Walking Climbing Camping Biking Bag MATERIAL- Polyester ,Water-resistant Polyester as the fabric do not allow water to easily penetrate.HELMET NET COVER included. CAPACITY- 12L (732 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 POCKETS-1 Main compartment, 2 front pockets and 2 mesh side pockets to keep your stuff separate and organized. HYDRATION SYSTEM COMPATIBLE- Internal hydration bladders compartment and water tube outlet (bladder not included).