Synchronization timescale (T_sync; top), ratio of the He star spin period to the orbital period (P₁/P_orb; middle), and BH spin magnitude (χ₂; bottom) are shown as functions of the central helium abundance. We consider three He star models: He ZAMS (solid line), a He star with 10% central helium depleted (dashed line), and a He star with 30% central helium depleted (dash-dotted line). All three models assume an initial orbital period of 1.0 day. The first column shows the results at 1.0 Z_⊙, while the second column shows those at 0.1 Z_⊙. The results at 0.01 Z_⊙ are nearly identical to the 0.1 Z_⊙ case, and are therefore not shown here.