The fibres of carbon used to provide strength to a wide variety of lightweight manufactured products such as sports equipment. There are several manufacturing processes: Rayon fibres with a high-modulus are charred around 300ºC, carbonized between 1,000ºC and 2,000ºC, and heat-stretched at 3,000ºC. Fibres made from polyacrylonitrile result in a product with lesser mechanical properties but improved yield and follow a similar process. They can also be made from molten coal and heavy petroleum hydrocarbons in which fibres are spun from the liquid in oxygen with heat treatment at 3,000ºC.