Correlation between radio luminosity of the brightest FIRST source within a projected physical radius of 50 kpc from the cluster center (BCG position in the maxBCG sample) and cluster mass for three sub-samples of galaxy clusters. Diamonds indicate maxBCG clusters in the redshift range 0.1 < z ≤ 0.2, and the best-fit correlation is indicated by the dotted line. This is consistent with the X-ray sample in the same redshift range (triangles). Fixing the slope, the correlation is consistent with a local sub-sample of X-ray clusters (0.01 < z ≤ 0.1, squares), where the luminosity level is lower due to a different luminosity cutoff in this sub-sample.