Comparison of different mass proxies for cluster XMMU J1230.3+1339. The combined mass estimate   ×  10¹⁴   M_⊙, shown on top with 1σ uncertainties (dashed lines), is based on the combination of four quasi independent mass proxies (red points). The numbering along the vertical axis is equivalent to the mass estimate labels (ME 1 − 13) in the text. Statistical 1σ uncertainties are shown by the black horizontal lines. The magnitude and direction of potential systematic offsets are displayed by the slightly shifted blue bars extending the statistical error for illustration purposes.