carbon fibres type UHM

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 $C 11$ value of graphite).

Source:

PAC, 1995, 67, 473 (Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)) on page 482