(a) Unfolded NuSTAR spectra of MAXI J1535-571. FPMA and FPMB data are plotted in black and red, respectively. (b) Data/model residuals to an absorbed cutoff power-law model. The narrow core of the iron line peaks at ∼6.5 keV. The energies of neutral Fe ﹩{\rm{K}}\alpha ﹩ (6.4 keV) and Fe XXV ﹩{\rm{K}}\alpha ﹩ (6.7 keV) are marked as orange dashed lines.