Comparison of the flux densities at 150 and 1400 MHz for the mETGs. The small red dots mark the upper limits for the sources that are not detected at 1.4 GHz. The two clusters of upper limits correspond to the sources that are undetected by either the FIRST or the NVSS. The two black crosses represent the typical errors on the flux density measurements, which are ∼10% on F₁₅₀ and ∼30% and ∼5% for high and low values of F₁₄₀₀, respectively. The blue diamonds mark the extended sources at 150 MHz. The lines represent the loci of constant spectral index.