Comparison of observed light-element ejecta to theoretical predictions. In green, we show the one, two, and three sigma contours of the distribution of neon-to-oxygen and magnesium-to-oxygen mass ratios in the ejecta of Vela, based on the 2TNT model. The locations of the individual bins in this parameter space are indicated with black dots. This is compared to the predicted total element ratios for individual explosions in the simulations by Sukhbold et al. (2016), where the color coding of the circular markers indicates the simulated progenitor mass.