Comparison of the inferred velocity dispersion of the ICM in the core of clusters derived from low-energy vs. higher-energy spectral lines. In particular, we plot the ratio of spectral-fit LoS velocity dispersions using two different X-ray bands: [6.7−8.0] keV versus [6.4−6.7] keV, as a function of SMBH mass. The solid line represents the median relation, whereas the shaded area specifies the 16th−84th envelope. For the Perseus-like sample, the ratio is systematically larger than 1, although by only 6−10%.