Top: limits on an additional Gaussian flux component at 3.55 keV for all clusters in the sample. Bottom: limits on the mixing angle in case of a 7.1 keV sterile neutrino. The limits are calculated separately for ACIS-S and ACIS-I, which are indicated by -s or -i following the cluster identification on the x-axis. Most lower limits and some best-fit values lie outside the plotted range. The dashed line shows the Bulbul et al. (2014) detection in their full XMM-Newton MOS sample. Limits show the 1σ (small symbols) and 3σ (big symbols) confidence range.