(B_max-V_max) colour vs. M_Bmax of a sample of sub-luminous SNe Ia (91bg-like) and transitional or 86G-like SNe from the Carnegie Supernova Project-I sample of Krisciunas et al. (2017). The magnitudes were derived using SNOoPy light curve fits, and the absolute magnitudes were calculated assuming H₀ = 67.8 km s⁻¹ Mpc. Magnitudes of SNe 1991bg, 2018cqj, 2018fhw, 1992A, 2011fe, and 2016jae are also plotted.