^b Multiwalled carbon nanotubes have the highest tensile strength of any material yet measured, with labs producing them at a tensile strength of 63 GPa,^[21] still well below their theoretical limit of 300 GPa^{[citation needed]}. The first nanotube ropes (20mm in length) whose tensile strength was published (in 2000) had a strength of 3.6 GPa.^[22] The density depends on the manufacturing method, and the lowest value is 0.037 or 0.55 (solid).^[23

^{http://en.wikipedia.org/wiki/Ultimate_tensile_strength}

 ^{Itt van, ebben a jó kis cikkben.}