Synthetic radio flux densities (lines) for models MOD-B1 (left panels) and Mod-B100 (right panels) plotted against the observed values (symbols) at 2.4 GHz (upper panels; Zanardo et al. 2010) and 8.6 GHz (lower panels; Zanardo et al. 2010; Ng et al. 2013). The figure shows the synthetic lightcurves (solid lines), the contribution to emission from the forwardshock traveling through the H II region (dashed lines) and through the ring (dot-dashed lines), and the contributionfrom the reverse shock traveling through the ejecta (dotted lines).