For an efficient insulation in furnaces extremely lightweight materials with high thermal shock stability which are made of graphite and carbon fibre reinforced carbon are used in furnaces used industrially at high and extremely high temperatures. In addition to their high temperature stability of up to more than 3,000°C and their excellent thermal shock stability they are characterized by a mass which is very low compared with metals. For this reason, these components cannot only be moved much more easily, they also have a very low thermal mass and, hence, increase the efficiency and the controllability of the furnace. On the other hand, they do not entail one typical disadvantage of ceramic high temperature materials – they can be joined with connection elements made of the same type of material, such as e.g. screws. This permits a modular structure which can be adjusted to the respective furnace and furnace load quickly and individually. CFC screws can be used at temperatures of up to 2,000°C without any loss of tensile, compressive and flectional strength. Their anisotropic thermal expansion behaviour leads to the self-fastening of the graphite/ CFC compounds even in case of cyclic thermal stresses. Hence, the connection and the power transmission are safe in a cold and hot state.