Our best-fit effective temperatures for young (<300 Myr; blue) and old (≥300 Myr; orange) benchmarks based on the Sonora Diamondback models (left) and the SM08 models (right). The empirical T_eff–spectral type relation established for young and field-age objects by A. Sanghi et al. (2023) is shown as dashed and solid lines, respectively. Spectral fitting results from D. C. Stephens et al. (2009) are overlaid as open black circles. For targets with identical spectral types and best-fit T_eff values, data points are slightly offset toward the upper right in these panels.