Nebular phase spectrum of SN 2022ngb at +252 days from explosion (black line), compared with synthetic spectra from the He-star models of Barmentloo et al. (2024). All spectra are normalized to their maximum flux and have the continuum removed. Left panel: Comparison of the nebular spectrum of SN 2022ngb with He-star models of varying M_preSN. Right panel: A detailed comparison of the [O I] and [N II] line profiles. The green and orange solid lines represent Gaussian fits to the [O I] and [N II] components, respectively. The emission lines from the H II region of the host galaxy is removed for a better comparison.