Carbon fibre is a mix of materials of different chemical compositions that when joined together create a product with certain chemical, physical, and mechanical properties. The resulting material is ultra light, stiff, and extremely strong. Each piece of carbon fibre is made up of thousands of single threads, each of which is made up of 92% carbon, features a cylindrical shape, and a diameter of 5-8 micrometres. The production of carbon fibre follows strict quality guidelines to guarantee its resistance and strength. Many production facilities verify each product by passing it through an X-ray in order to guarantee there are no imperfections that are not visible to the eye. Carbon fibre was introduced to the market in 1963, and together with fibre glass brought in the era of advanced composite materials. Initially both materials were used for military and aeronautic applications, but very quickly spread to the automobile sector and beyond.