Best explosion parameters (E_K, M_ej, M⁵⁶Ni) from the Arnett models of 33 CSP-I SE SNe as computed using v_ph from Fe ii versus those computed using V_m from He i and O i as explained in Dessart et al. (2016). SNe IIb, Ib, Ic, and Ic-BL are represented in green, blue, red, and magenta, respectively. The dashed lines indicate when the parameters are identical with the two methods. Identical ⁵⁶Ni masses are derived and very similar ejecta masses, whereas the energy obtained with the velocities from He i and O i are typically larger than those obtained with the Fe ii velocity, especially for SNe Ic.