PPD of the black hole spin magnitude distribution in the Gaussian Isotropic Cut model. Blue shows the magnitude distribution of the low-mass Gaussian component (parameterized by μ_χ and σ_χ), orange that of the low-mass isotropic component (﹩{\mu }_{\chi }^{{\rm{Iso}}}﹩ and ﹩{\sigma }_{\chi }^{{\rm{Iso}}}﹩), and purple that of the high-mass isotropic component (﹩{\mu }_{\chi }^{{\rm{HighIso}}}﹩ and ﹩{\sigma }_{\chi }^{{\rm{HighIso}}}﹩). The transition between low- and high-mass components is inferred at a primary mass cutoff of ﹩\tilde{m}\approx 44.{3}_{-4.6}^{+8.7}\,{M}_{\odot }﹩. The green color shows the nonparametric B-spline model of The LIGO, Virgo, and KAGRA Collaborations (2025a, 2025e ). Solid lines and shaded envelopes indicate medians and 90% credible intervals, respectively. The dotted lines show the prior bounds of the single-component models.