Evolution of the shocked ejecta mass (in units of M_⊙) in log scale for various species as derived from models B18.3 (top panel) and B18.3-Dec (bottom). Different colors represent specific elements, as indicated by the labels. The black solid, dashed, and dotted lines represent the total shocked ejecta mass, the shocked CSM mass (including the H II region and the rings), and the mass of shocked material from the equatorial ring, respectively. Due to their low mass content, Ar, Cr, and Ti are barely visible in the figure.