Core-excised gas mass fraction f_gas,ce vs. halo mass M₅₀₀ of XUCS sample with fits to other samples. The black line with shading (error) represents the Andreon (2010) fit to clusters in Vikhlinin et al. (2006) and Sun et al. (2009), the red line represents the Landry et al. (2012, dashed lines indicate scatter) fit to their sample, and the green line represents the XXL 100 brightest clusters (Eckert et al. 2016, dashed lines indicate uncertainty); see text for details. Blue points are clusters that are brighter in X-ray than the average for their mass.