Spectral comparison between SN 2018bsz at –9 day (from maximum light) and SLSNe of the best SNID matches together with three well observed, nearby literature events, and a well-observed fast-evolving SLSN-I. The rest wavelength of the three most prominent C II lines are shown by dotted black lines, while the peaks and troughs of the w-shaped O II feature for SN 2018bsz are indicated by dashed and dotted grey lines respectively. The latter enables a direct comparison to the peaks and troughs found in other SLSNe-I. References: PTF12dam (Quimby et al. 2018); PTF10aagc (Quimby et al. 2018); SN 2009jh (Quimby et al. 2018), these first three are smoothed spectra; SSS120810 (full name SSS120810-231802-560926, Nicholl et al. 2014), Gaia16apd (Kangas et al. 2017); SN 2015bn (Nicholl et al. 2016); SN 2017egm (Bose et al. 2018); LSQ14mo (Chen et al. 2017a).