If ordering for delivery outside the UK there is an option for Tracked International Shipping. If you do not order and pay for Tracked shipping and your order is a few days late, please do not ask for the Tracking number! Thank you.A range of 6 sizes of pyrolytic graphite squares measuring from 10 mm x 10 mm up to 25 mm x 25 mm. Each square face dimension is -0.0 / +0.5 mm.The thickness of each square listed are manufactured to tolerances of 1 mm -0.0 mm / +0.1 mm.Any piece of pyrolytic graphite from 0.25 mm up to about 2 mm will levitate indefinitely, without any form of outside assistance. The height of the levitation depends on the strength of the magnets and thickness of the pyrolytic graphite.All of our pyrolyic graphite can be used as very efficient and effective heat sinks, due to the high thermal conductivity along the A-B plane of 400 W/(m2. K/m).The pyrolytic graphite is perfectly shaped, as manufactured at the factory.The edges are smooth right angles to the faces.If you require thinner squares such as 0.5 mm, or thicker squares such as 1.25 mm please email us through the eBay messaging service.Have a look at our pyrolytic graphite, on our levitation demonstrators in our promotional video that we uploaded onto You Tube: http://www.youtube.com/watch?v=fBuAjE_sCtA If you want a mixture of different size squares, or discs, or a larger total quantity of pyrolytic graphite, please email for our very best price.Enjoy. Squares: Size mm Area cm2 Cost £ £/cm2 25 x 25 6.25 13.95 2.23 20 x 20 4.00 10.95 7.74 16 x 16 2.56 8.95 4.50 12 x 12 1.44 6.95 4.83 10 x 10 1.00 5.95 5.95 Pyrolytic Graphite Pyrolytic carbon is high purity carbon, it exhibits high permeability, corrosion resistance, crystal orientation as well as heat, electricity, magnetism properties and is extremely anisotropic. Pyrolytic graphite is a unique form of graphite manufactured by decomposition of Methane gas at very high temperature, approximately 2000 degrees celcius, in a vacuum furnace. The result is an ultra-pure product which is near theoretical maximum density. The material is grown one atomic layer at a time at the rate of 1/40 mm an hour onto a substrate giving it a layered composition. The layers of carbon atoms form crystals of hexogonal sheets. 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. Pyrolytic graphite is the most diamagnetic (450 x 10-6) against the cleavage plane, exhibiting the greatest diamagnetism (by weight) of any room-temperature diamagnet. Bismuth is second highest at (170 x 10-6).Diamagnetic materials create an induced magnetic field in a direction opposite to an externally applied magnetic field, and are repelled by the applied magnetic field. In contrast, the opposite behaviour is exhibited by paramagnetic materials. Diamagnetism is a quantum mechanical effect that occurs in all materials; where it is the only contribution to the magnetism the material is called a diamagnet. Unlike a ferromagnet, a diamagnet is not a permanent magnet. Its magnetic permeability is less than μ0 (the permeability of free space).Diamagnets were first discovered when Sebald Justinus Brugmans observed in 1778 that bismuth and antimony were repelled by magnetic fields. The term diamagnetism was coined by Michael Faraday in September 1845, when he realized that every material responded (in either a diamagnetic or paramagnetic way) to an applied magnetic field. PROPERTYMETRIC VALUEDensity2.2gr / cm 3Flexural Strength – AB89.6mpaCompressive Strength – AB103.4mpaCompressive Strength – C172.4mpaShear Strength – AB6.9mpaCTE – AB0.5Microns / m ° CCTE – C6.5Microns / m ° CThermal Conductivity – AB400W / (m 2. K / m)Thermal Conductivity – C3.5W / (m 2. K / m)Resistivity (RT) – AB0.5 * 10-3ohm / cmResistivity (1650C) – AB0.3 * 10-3ohm / cmResistivity (RT) – C0.5ohm / cmResistivity (1650C) – C0.3ohm / cm