carbon fibres type UHM

https://doi.org/10.1351/goldbook.C00837
Carbon fibres type UHM (ultra-high modulus) designates a class of
carbon fibres
having very high values of
Young's modulus
larger than 600 GPa (i.e. greater than 55% of the theoretical C11 value of
graphite
).
Source:
PAC, 1995, 67, 473. (Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)) on page 482 [Terms] [Paper]