These cylinders are known as semi-composite or type 2 cylinders. In producing this type of cylinder, a steel cylinder is used as the lining layer made of steel and the cylindrical part of this cylinder is covered with carbon fibers. This company in cooperation with Navid Composite Materials Company has succeeded to produce type 2 cylinders using carbon fibers. Carbon fibers show high strength against heat, so that they are known as non-explosive fibers. The light weight of carbon fibers makes it possible to enhance CNG cylinders while maintaining their light weight, stiffness, rigidity and resistance with low thermal expansion coefficient that gives enhanced safety to the cylinders in order to be used in autobuses. Given the applications of this cylinder in autobuses, this product is also known as autobus cylinder. Since carbon fibers are used in production of this cylinder, the weight of this cylinder is 30% less than full steel cylinders. TAVANA Company is the first producer of this type of cylinder in Iran.