Pyrolytic Graphite is a unique form of graphite manufactured by decomposition of a hydrocarbon gas at very high temperature in a vacuum furnace. The result is an ultra-pure product which is near theoretical density and extremely anisotropic. The material is grown onto a substrate giving it a layered composition. This also means it has different properties in different planes. In the C plane (across its layers) it has low thermal conductivity, acting as an insulator. In the A-B plane (with the layers) it has very high thermal conductivity, acting as a superb conductor.