W1-W2 and W2 magnitudes shown for the eRASS1 hard sample. All hard sources with p_any less than the threshold of 0.033 are shown as blue unfilled circles, and sources with good p_any are as with blue filled circles. Hard-only sources with p_any less than the threshold of 0.061 are shown as orange unfilled squares, and hard-only sources with good p_any are shown as orange filled squares. Tracks as in Salvato et al. (2022) and Fig. 12 of this work are shown in various line styles and colours. Redshift ticks can be found at z = 0.04, 0.2, 0.4, 0.92, and where available at z = 1.4, 3.8.