Shane/Kast red optical spectra (black lines) of TOI-2084 (left) and its wide stellar companion TOI-2084B (right) compared to the best-fit M2 and M8 SDSS spectral templates from Bochanski et al. (2007, magenta lines). The lower panels display the difference between these spectra (black line) compared to the ±1σ measurement uncertainty (grey band). Key features are labeled, including the strong telluric O₂ band at 7600 Å (⊕). Inset boxes show close-ups of the region around the 6563 Å Hα and 6708 Å Li I lines.