Normalized mass distributions of hydrogen (dark green), helium (magenta), carbon (green), oxygen (red), silicon (blue), titanium (cyan), and “nickel” (black) versus radial velocity for models W15-2-cw (top left), L15-1-cw (bottom left), N20-4-cw (top right), and B15-1-pw (bottom right) at the shock breakout time. The radial velocity bins Δv_r are 100 km s^-1 wide, and the normalized mass is given for each velocity bin.